Reorganization of spinlock defines

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Prompted by confusion over Itanium/Opterion, I have written a patch to
improve the way we define spinlocks for platforms and cpu's.

The main.c part of the patch strikes me as irrelevant to the claimed
purpose and unlikely to accomplish anything except breaking things.
Do you have a system the main.c "__alpha" code is relevant to, on which
to test that you did not break it?

Other than that, it looks like basically a good idea. But...

I plan to apply this to 7.4.

This seems like living dangerously. You do realize that this patch will
invalidate our trust that the code works on every single supported
platform? I think beta3 may be a bit late in the game for this sort of
thing, because we've already gotten a good bit of the testing we can
expect to get for lesser-used platforms during this beta cycle.

At the very least I'd like to see the decision discussed on -hackers
and not buried in -patches.

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Prompted by confusion over Itanium/Opterion, I have written a patch to
improve the way we define spinlocks for platforms and cpu's.

The main.c part of the patch strikes me as irrelevant to the claimed
purpose and unlikely to accomplish anything except breaking things.
Do you have a system the main.c "__alpha" code is relevant to, on which
to test that you did not break it?

Other than that, it looks like basically a good idea. But...

I was going to have an alpha guy test it --- that was the one change I
wasn't sure about. We did test for __alpha__ all over the port/*.h
files, so it wasn't clear which alpha's were being hit. I can throw in
a comment and skip that part --- not sure.

I plan to apply this to 7.4.

This seems like living dangerously. You do realize that this patch will
invalidate our trust that the code works on every single supported
platform? I think beta3 may be a bit late in the game for this sort of
thing, because we've already gotten a good bit of the testing we can
expect to get for lesser-used platforms during this beta cycle.

At the very least I'd like to see the decision discussed on -hackers
and not buried in -patches.

The problem with waiting for 7.5 is that we will have no error reporting
when our non-spinlock code is being executed, and with Opteron/Itanium,
it seems like a good time to get it working. We had the FreeBSD report
with not finding Opteron/Itanium, and that's what got me going. Also,
if it doesn't find the spinlock code, it will report an error, so we
should flesh this all out as we collect supported platforms, which we
haven't started yet.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

This is the email describing the changes in the patch for 7.4.

---------------------------------------------------------------------------

Bruce Momjian wrote:

Prompted by confusion over Itanium/Opterion, I have written a patch to
improve the way we define spinlocks for platforms and cpu's. It
basically decouples the OS from the CPU spinlock code. In almost all
cases, the spinlock code cares only about the compiler and CPU, not the
OS.

The patch:

o defines HAS_TEST_AND_SET inside each spinlock routine, not in
platform-specific files
o moves slock_t defines into the spinlock routines
o remove NEED_{CPU}_TAS_ASM define because it is no longer needed
o reports a compile error if spinlocks are not defined
o adds a configure option --without-spinlocks to allow
non-spinlock compiles

Looking at the patch, I realize this is how we should have done it all
along.

It would be nice to report the lack of spinlocks in configure, rather
than during the compile, but I can't compile s_lock.h and test for
HAS_TEST_AND_SET until configure completes.

I plan to apply this to 7.4.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

The problem with waiting for 7.5 is that we will have no error reporting
when our non-spinlock code is being executed, and with Opteron/Itanium,
it seems like a good time to get it working.

Well, as long as you're prepared to reduce the list of known supported
platforms to zero as of 7.4beta3, and issue a fresh call for port reports.

But it seems to me that this is mostly a cosmetic cleanup and therefore
not the kind of thing to be doing late in beta. Couldn't we do
something that affects only Opteron/Itanium and doesn't take a chance
on breaking everything else?

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

The problem with waiting for 7.5 is that we will have no error reporting
when our non-spinlock code is being executed, and with Opteron/Itanium,
it seems like a good time to get it working.

Well, as long as you're prepared to reduce the list of known supported
platforms to zero as of 7.4beta3, and issue a fresh call for port reports.

I haven't collected any known reports yet. That happens later, I
thought, nearer to RC1.

But it seems to me that this is mostly a cosmetic cleanup and therefore
not the kind of thing to be doing late in beta. Couldn't we do
something that affects only Opteron/Itanium and doesn't take a chance
on breaking everything else?

Yes, but to throw an error if spinlocks aren't found, we need this
patch. We would have to test for Opteron in all the platforms that test
for specific CPU's but don't test for opteron, and might support
opterion/itanium, but even then, we don't have any way of getting a
report of a failure.

Yea, I should have thought of this before beta1, but now that I see the
bug reports, seems we have to go this way.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

On Thu, 11 Sep 2003, Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

The problem with waiting for 7.5 is that we will have no error reporting
when our non-spinlock code is being executed, and with Opteron/Itanium,
it seems like a good time to get it working.

Well, as long as you're prepared to reduce the list of known supported
platforms to zero as of 7.4beta3, and issue a fresh call for port reports.

I didn't think we had done that yet ... had we? called for port reports,
that is ... ?

But it seems to me that this is mostly a cosmetic cleanup and therefore
not the kind of thing to be doing late in beta. Couldn't we do
something that affects only Opteron/Itanium and doesn't take a chance
on breaking everything else?

I just went through the whole patch myself, and as much as I like the
overall simplification, I tend to agree with Tom here on questioning the
requirement to do suck a massive change so late in the end cycle ... is
there no smaller bandaid that can be applied to handle the Opteron/Itanium
issue for v7.4, with the "cleanup patch" being applied right away after
v7.4?

Marc G. Fournier wrote:

But it seems to me that this is mostly a cosmetic cleanup and therefore
not the kind of thing to be doing late in beta. Couldn't we do
something that affects only Opteron/Itanium and doesn't take a chance
on breaking everything else?

I just went through the whole patch myself, and as much as I like the
overall simplification, I tend to agree with Tom here on questioning the
requirement to do suck a massive change so late in the end cycle ... is
there no smaller bandaid that can be applied to handle the Opteron/Itanium
issue for v7.4, with the "cleanup patch" being applied right away after
v7.4?

Well, the problem was that we defined HAS_TEST_AND_SET inside the ports.
I guess we could splatter a test for Itanium and Opterion in every port
that could possibly use it, but then again, if we fall back to not
finding it for some reason, we don't get a report because we silently
fall back to semaphores. That's what has me worried, that if we don't
do it, we will not know what platforms really aren't working properly.

Take FreeBSD for example, that couldn't find Opteron. It lists every
cpu like this:

#if defined(__i386__)
#define NEED_I386_TAS_ASM
#define HAS_TEST_AND_SET
typedef unsigned char slock_t;
#endif

#if defined(__sparc__)
#define NEED_SPARC_TAS_ASM
#define HAS_TEST_AND_SET
typedef unsigned char slock_t;
#endif

We would have to add an opteron/itanium to port that does this, but if
we miss some opteron/itanium define, we might never know because of the
silent fallback.

I don't care if we save it for 7.5 --- I just don't know how we will be
sure we have things working properly without it.

We could apply it tomorrow and see how things look on Monday.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

--On Thursday, September 11, 2003 23:46:56 -0300 "Marc G. Fournier"
<scrappy@postgresql.org> wrote:

On Thu, 11 Sep 2003, Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

The problem with waiting for 7.5 is that we will have no error
reporting when our non-spinlock code is being executed, and with
Opteron/Itanium, it seems like a good time to get it working.

Well, as long as you're prepared to reduce the list of known supported
platforms to zero as of 7.4beta3, and issue a fresh call for port
reports.

I didn't think we had done that yet ... had we? called for port reports,
that is ... ?

But it seems to me that this is mostly a cosmetic cleanup and therefore
not the kind of thing to be doing late in beta. Couldn't we do
something that affects only Opteron/Itanium and doesn't take a chance
on breaking everything else?

I just went through the whole patch myself, and as much as I like the
overall simplification, I tend to agree with Tom here on questioning the
requirement to do suck a massive change so late in the end cycle ... is
there no smaller bandaid that can be applied to handle the Opteron/Itanium
issue for v7.4, with the "cleanup patch" being applied right away after
v7.4?

Bruce sent me a copy of the patch, and it ****BREAKS**** UnixWare (If y'all
care).

LER

--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749

On Thu, 11 Sep 2003, Bruce Momjian wrote:

Yes, but to throw an error if spinlocks aren't found, we need this
patch. We would have to test for Opteron in all the platforms that test
for specific CPU's but don't test for opteron, and might support
opterion/itanium, but even then, we don't have any way of getting a
report of a failure.

'K, but apparently right now we are broken on Opteron/Itanium without this
patch ... so, to fix, we either:

a. add appropriate tests to the individual port files based on individual
failure reports (albeit not clean, definitely safer), or:

b. we do massive, sweeping changes to the whole HAVE_TEST_AND_SET
detection code (definitely cleaner, but has potential of breaking more
then it fixes) :(

personally, as late in the cycle as we are, I think that a. is the wiser
move for v7.4, with b. being something that should happen as soon as
possible once we've branched and start working on v7.5 ...

"Marc G. Fournier" <scrappy@postgresql.org> writes:

On Thu, 11 Sep 2003, Tom Lane wrote:

Well, as long as you're prepared to reduce the list of known supported
platforms to zero as of 7.4beta3, and issue a fresh call for port reports.

I didn't think we had done that yet ... had we? called for port reports,
that is ... ?

We hadn't, no. My point is that in the past we've continued to list
platforms as supported if we've had a successful report in the past
release or two. Fooling with the spinlock code is delicate enough
that I'd want to insist on moving everything to the "unsupported"
category until we get a success report with the modified code.

Maybe we should just do that. It's likely that the only platforms
that end up marked unsupported are ones that no one cares about any
more anyway. But I think we have to realize that this is not a
trivial set of changes, even if it looks like it "should work".
(Which it does, just for the record. I'm just feeling paranoid
because of where we are in the release cycle.)

regards, tom lane

Bruce Momjian <pgman@candle.pha.pa.us> writes:

I guess we could splatter a test for Itanium and Opterion in every port
that could possibly use it, but then again, if we fall back to not
finding it for some reason, we don't get a report because we silently
fall back to semaphores. That's what has me worried, that if we don't
do it, we will not know what platforms really aren't working properly.

Agreed, the silent fallback to semaphores isn't such a hot idea in
hindsight. But the part of the patch that requires a configure option
to use that code path could be applied without touching anything else.

regards, tom lane

Larry Rosenman <ler@lerctr.org> writes:

Bruce sent me a copy of the patch, and it ****BREAKS**** UnixWare (If y'all=
=20
care).

Unfixably? Or just a small oversight?

I'm actually not worried about platforms that are actively being tested.
It's the stuff that hasn't been confirmed recently that is going to be
at risk.

regards, tom lane

Tom Lane wrote:

Larry Rosenman <ler@lerctr.org> writes:

Bruce sent me a copy of the patch, and it ****BREAKS**** UnixWare (If y'all=
=20
care).

Unfixably? Or just a small oversight?

I'm actually not worried about platforms that are actively being tested.
It's the stuff that hasn't been confirmed recently that is going to be
at risk.

I sent him a new patch just now.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

--On Thursday, September 11, 2003 23:13:54 -0400 Tom Lane
<tgl@sss.pgh.pa.us> wrote:

Larry Rosenman <ler@lerctr.org> writes:

Bruce sent me a copy of the patch, and it ****BREAKS**** UnixWare (If
y'all= =20
care).

Unfixably? Or just a small oversight?

I'm actually not worried about platforms that are actively being tested.
It's the stuff that hasn't been confirmed recently that is going to be
at risk.

I'm seeing failures with the 2nd patch as well. Seems like it's not liking
UnixWare's
cc defines.

the documentation is at:

http://www.lerctr.org:8458/

the cc man page is at:

http://www.lerctr.org:8458/en/man/html.1/cc.1.html

Tom, You still have an account here.

Bruce, if you'd like an account, that is easily arranged.

LER

regards, tom lane

--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

I guess we could splatter a test for Itanium and Opterion in every port
that could possibly use it, but then again, if we fall back to not
finding it for some reason, we don't get a report because we silently
fall back to semaphores. That's what has me worried, that if we don't
do it, we will not know what platforms really aren't working properly.

Agreed, the silent fallback to semaphores isn't such a hot idea in
hindsight. But the part of the patch that requires a configure option
to use that code path could be applied without touching anything else.

Yes, we could do just the configure warning, then plaster tests into the
port files to try to hit all the opteron/itanium cases. I am a little
concerned that this might throw up a bunch of problem cases that we will
patching for a while.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Yes, we could do just the configure warning, then plaster tests into the
port files to try to hit all the opteron/itanium cases. I am a little
concerned that this might throw up a bunch of problem cases that we will
patching for a while.

Probably so --- but we'd only be breaking new platforms that people are
starting to use, not old ones that might not be getting tested
regularly.

Understand that I'm not dead set against applying this patch for 7.4.
(On a code-cleanliness point of view I favor it.) What I want is some
open discussion about the risks and benefits before we decide.

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Yes, we could do just the configure warning, then plaster tests into the
port files to try to hit all the opteron/itanium cases. I am a little
concerned that this might throw up a bunch of problem cases that we will
patching for a while.

Probably so --- but we'd only be breaking new platforms that people are
starting to use, not old ones that might not be getting tested
regularly.

Looking at the code, I wonder if we already have folks not using
spinlocks, and not even knowing it. I don't think problem reports will
be limited to new platforms.

Understand that I'm not dead set against applying this patch for 7.4.
(On a code-cleanliness point of view I favor it.) What I want is some
open discussion about the risks and benefits before we decide.

Sure, and I am not pushing the patch. I am just saying it would have
been ideal a few weeks ago --- I am not sure if we are worse off with or
without it.

I just learned from Larry that Unixware defines intel as i386, not
__i386 or __i386__, at least of the native SCO compiler that he uses.

What the code used to do is define NEED_I386_TAS_ASM unconditionally on
some platforms (negating the need to test for a compiler symbol) or test
for each platform compiler symbol (and not test all possible ways it
could be specified), like FreeBSD did. That's why things are so messy.
I am going to test for __cpu, __cpu__, and cpu on non-gcc compiler for
consistency. It is only done in one place in the patch, so that should
be good.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Looking at the code, I wonder if we already have folks not using
spinlocks, and not even knowing it. I don't think problem reports will
be limited to new platforms.

Very likely --- I heard from someone recently who was trying to run
HPUX/Itanium. After we got past the hard-wired assumption that HPUX
== HPPA, it was still giving lousy performance for lack of spinlocks.
I like the part of the patch that is in-your-face about that.

I just learned from Larry that Unixware defines intel as i386, not
__i386 or __i386__, at least of the native SCO compiler that he uses.

[blink] Namespace infringement 'r us, huh?

I am going to test for __cpu, __cpu__, and cpu on non-gcc compiler for
consistency. It is only done in one place in the patch, so that should
be good.

Please, only the first two. Make the Unixware template add __i386__.
Don't add assumptions about valid user-namespace symbols.

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Looking at the code, I wonder if we already have folks not using
spinlocks, and not even knowing it. I don't think problem reports will
be limited to new platforms.

Very likely --- I heard from someone recently who was trying to run
HPUX/Itanium. After we got past the hard-wired assumption that HPUX
== HPPA, it was still giving lousy performance for lack of spinlocks.
I like the part of the patch that is in-your-face about that.

I just learned from Larry that Unixware defines intel as i386, not
__i386 or __i386__, at least of the native SCO compiler that he uses.

[blink] Namespace infringement 'r us, huh?

I am going to test for __cpu, __cpu__, and cpu on non-gcc compiler for
consistency. It is only done in one place in the patch, so that should
be good.

Please, only the first two. Make the Unixware template add __i386__.
Don't add assumptions about valid user-namespace symbols.

Roger!

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

--On Thursday, September 11, 2003 23:42:53 -0400 Tom Lane
<tgl@sss.pgh.pa.us> wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Looking at the code, I wonder if we already have folks not using
spinlocks, and not even knowing it. I don't think problem reports will
be limited to new platforms.

Very likely --- I heard from someone recently who was trying to run
HPUX/Itanium. After we got past the hard-wired assumption that HPUX
== HPPA, it was still giving lousy performance for lack of spinlocks.
I like the part of the patch that is in-your-face about that.

I just learned from Larry that Unixware defines intel as i386, not
__i386 or __i386__, at least of the native SCO compiler that he uses.

[blink] Namespace infringement 'r us, huh?

Yeah. I **DO** have SCO's ear on it, but I don't know how far I'll get,
plus there are
TONS of pre-whenever-we-get-it-fixed out there.

I am going to test for __cpu, __cpu__, and cpu on non-gcc compiler for
consistency. It is only done in one place in the patch, so that should
be good.

Please, only the first two. Make the Unixware template add __i386__.
Don't add assumptions about valid user-namespace symbols.

that's reasonable. At least until 64-bit UnixWare. :-)

(announced at SCOForum).

regards, tom lane

---------------------------(end of broadcast)---------------------------
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--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749

Larry Rosenman <ler@lerctr.org> writes:

Please, only the first two. Make the Unixware template add __i386__.
Don't add assumptions about valid user-namespace symbols.

that's reasonable. At least until 64-bit UnixWare. :-)

Even then, I'd prefer to put the necessary kluge into template/unixware
or Makefile.unixware or port/unixware.h, rather than add a risky
assumption globally.

regards, tom lane

--On Friday, September 12, 2003 00:00:43 -0400 Tom Lane <tgl@sss.pgh.pa.us>
wrote:

Larry Rosenman <ler@lerctr.org> writes:

Please, only the first two. Make the Unixware template add __i386__.
Don't add assumptions about valid user-namespace symbols.

that's reasonable. At least until 64-bit UnixWare. :-)

Even then, I'd prefer to put the necessary kluge into template/unixware
or Makefile.unixware or port/unixware.h, rather than add a risky
assumption globally.

Sure, and 64-bit UnixWare is 2 years out any way.

Hopefully we can get reasonableness by then.

I've already sent a whine-a-gram to the compiler guys at SCO.

LER

regards, tom lane

--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749

Larry Rosenman <ler@lerctr.org> writes:

I've already sent a whine-a-gram to the compiler guys at SCO.

Prolly you thought of this already, but: getting them to *add*
an implicit #define of __i386__ should be plenty easy compared
to getting them to *remove* the one for i386. And while I think
they should remove the latter, the immediate problem would be
solved as soon as they add the former.

regards, tom lane

On Thu, 11 Sep 2003, Bruce Momjian wrote:

Well, the problem was that we defined HAS_TEST_AND_SET inside the ports.
I guess we could splatter a test for Itanium and Opterion in every port
that could possibly use it, but then again, if we fall back to not
finding it for some reason, we don't get a report because we silently
fall back to semaphores. That's what has me worried, that if we don't
do it, we will not know what platforms really aren't working properly.

From what I understand, "not working properly" means slow, not broken, no?
Which means ppl could submit a problem report and it could be fixed for
v7.4.1 ... its not so much 'not working properly' as it is 'not optimal
performance' ...

--On Friday, September 12, 2003 00:06:49 -0400 Tom Lane <tgl@sss.pgh.pa.us>
wrote:

Larry Rosenman <ler@lerctr.org> writes:

I've already sent a whine-a-gram to the compiler guys at SCO.

Prolly you thought of this already, but: getting them to *add*
an implicit #define of __i386__ should be plenty easy compared
to getting them to *remove* the one for i386. And while I think
they should remove the latter, the immediate problem would be
solved as soon as they add the former.

sure, and I expect that's what they may do. We'll see what they say.

LER

regards, tom lane

--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749

Marc G. Fournier wrote:

On Thu, 11 Sep 2003, Bruce Momjian wrote:

Well, the problem was that we defined HAS_TEST_AND_SET inside the ports.
I guess we could splatter a test for Itanium and Opterion in every port
that could possibly use it, but then again, if we fall back to not
finding it for some reason, we don't get a report because we silently
fall back to semaphores. That's what has me worried, that if we don't
do it, we will not know what platforms really aren't working properly.

From what I understand, "not working properly" means slow, not broken, no?

Which means ppl could submit a problem report and it could be fixed for
v7.4.1 ... its not so much 'not working properly' as it is 'not optimal
performance' ...

Right, though I am not sure people will know _slow_ configuration vs.
PostgreSQL is slow.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

On Thu, 11 Sep 2003, Bruce Momjian wrote:

I just learned from Larry that Unixware defines intel as i386, not
__i386 or __i386__, at least of the native SCO compiler that he uses.

could we put something in the various port files to standardize this? ie.
in unixware.h, add somethinglike:

#ifdef i386
#define __i386__
#endif

just so that 'special cases' are centralized in the ports file, and the
mainstream code doesn't have:

#if defined(i386) || defined(__i386) || defined(__i386__)

?

Marc G. Fournier wrote:

On Thu, 11 Sep 2003, Bruce Momjian wrote:

I just learned from Larry that Unixware defines intel as i386, not
__i386 or __i386__, at least of the native SCO compiler that he uses.

could we put something in the various port files to standardize this? ie.
in unixware.h, add somethinglike:

#ifdef i386
#define __i386__
#endif

just so that 'special cases' are centralized in the ports file, and the
mainstream code doesn't have:

#if defined(i386) || defined(__i386) || defined(__i386__)

Yep, that's what Tom wants and I am doing that now. I sent a patch to
Larry for testing.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

On Fri, 12 Sep 2003, Bruce Momjian wrote:

Marc G. Fournier wrote:

On Thu, 11 Sep 2003, Bruce Momjian wrote:

Well, the problem was that we defined HAS_TEST_AND_SET inside the ports.
I guess we could splatter a test for Itanium and Opterion in every port
that could possibly use it, but then again, if we fall back to not
finding it for some reason, we don't get a report because we silently
fall back to semaphores. That's what has me worried, that if we don't
do it, we will not know what platforms really aren't working properly.

From what I understand, "not working properly" means slow, not broken, no?

Which means ppl could submit a problem report and it could be fixed for
v7.4.1 ... its not so much 'not working properly' as it is 'not optimal
performance' ...

Right, though I am not sure people will know _slow_ configuration vs.
PostgreSQL is slow.

No, but definitely something for those discussion performance to add
to their checklist :)

BTW, post-compile, running system ... how do you check this? Or can you?

For instance, having a checklist, of sorts, that ppl can go through when
trying to investigate performance issues could include stuff like:

check swap usage (albeit obvious to alot of ppl, not to all)
check disk usage using iostat
check spinlocks in use using ... ??

"Marc G. Fournier" <scrappy@postgresql.org> writes:

Right, though I am not sure people will know _slow_ configuration vs.
PostgreSQL is slow.

No, but definitely something for those discussion performance to add
to their checklist :)

BTW, post-compile, running system ... how do you check this? Or can you?

If we force people to give a --without-spinlocks config option to build
that way, then `pg_config --configure' will reveal the dirty deed ...

regards, tom lane

Marc G. Fournier wrote:

From what I understand, "not working properly" means slow, not broken, no?

Which means ppl could submit a problem report and it could be fixed for
v7.4.1 ... its not so much 'not working properly' as it is 'not optimal
performance' ...

Right, though I am not sure people will know _slow_ configuration vs.
PostgreSQL is slow.

No, but definitely something for those discussion performance to add
to their checklist :)

BTW, post-compile, running system ... how do you check this? Or can you?

For instance, having a checklist, of sorts, that ppl can go through when
trying to investigate performance issues could include stuff like:

check swap usage (albeit obvious to alot of ppl, not to all)
check disk usage using iostat
check spinlocks in use using ... ??

We can add the compiler test that will throw an error if they aren't
using spinlocks, and they have to use a configure flag to enable it.
The only issue there is that this is going to throw up perhaps many
cases we haven't gotten working, and they might dribble out for weeks or
after final, while a clean solution could break more platforms in the
short term, but could catch more in the long term.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

New patch attached.

---------------------------------------------------------------------------

Bruce Momjian wrote:

Prompted by confusion over Itanium/Opterion, I have written a patch to
improve the way we define spinlocks for platforms and cpu's. It
basically decouples the OS from the CPU spinlock code. In almost all
cases, the spinlock code cares only about the compiler and CPU, not the
OS.

The patch:

o defines HAS_TEST_AND_SET inside each spinlock routine, not in
platform-specific files
o moves slock_t defines into the spinlock routines
o remove NEED_{CPU}_TAS_ASM define because it is no longer needed
o reports a compile error if spinlocks are not defined
o adds a configure option --without-spinlocks to allow
non-spinlock compiles

Looking at the patch, I realize this is how we should have done it all
along.

It would be nice to report the lack of spinlocks in configure, rather
than during the compile, but I can't compile s_lock.h and test for
HAS_TEST_AND_SET until configure completes.

I plan to apply this to 7.4.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Tom Lane wrote:

Larry Rosenman <ler@lerctr.org> writes:

Bruce sent me a copy of the patch, and it ****BREAKS**** UnixWare (If y'all=
=20
care).

Unfixably? Or just a small oversight?

Updated patch now works on Unixware.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

On Fri, 12 Sep 2003, Tom Lane wrote:

"Marc G. Fournier" <scrappy@postgresql.org> writes:

Right, though I am not sure people will know _slow_ configuration vs.
PostgreSQL is slow.

No, but definitely something for those discussion performance to add
to their checklist :)

BTW, post-compile, running system ... how do you check this? Or can you?

If we force people to give a --without-spinlocks config option to build
that way, then `pg_config --configure' will reveal the dirty deed ...

That's not quite what I meant :) Right now, if I understood what Bruce
was saying, if someone doesn't have spinlocks, it switches to using SysV
Messenging, correct? In the current system, is there anything that one
can do on a running, live system, to detect that you aren't using
spinlocks?

Marc G. Fournier wrote:

On Fri, 12 Sep 2003, Tom Lane wrote:

"Marc G. Fournier" <scrappy@postgresql.org> writes:

Right, though I am not sure people will know _slow_ configuration vs.
PostgreSQL is slow.

No, but definitely something for those discussion performance to add
to their checklist :)

BTW, post-compile, running system ... how do you check this? Or can you?

If we force people to give a --without-spinlocks config option to build
that way, then `pg_config --configure' will reveal the dirty deed ...

That's not quite what I meant :) Right now, if I understood what Bruce
was saying, if someone doesn't have spinlocks, it switches to using SysV
Messenging, correct? In the current system, is there anything that one
can do on a running, live system, to detect that you aren't using
spinlocks?

No. I don't think so.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

"Marc G. Fournier" <scrappy@postgresql.org> writes:

If we force people to give a --without-spinlocks config option to build
that way, then `pg_config --configure' will reveal the dirty deed ...

That's not quite what I meant :) Right now, if I understood what Bruce
was saying, if someone doesn't have spinlocks, it switches to using SysV
Messenging, correct? In the current system, is there anything that one
can do on a running, live system, to detect that you aren't using
spinlocks?

It'll be fairly obvious if you use "ipcs -s" and count up the number of
semaphores created by the postmaster. Ordinarily we will grab
approximately max_connections semas, but without spinlocks it will
be somewhere north of max_connections + 2 * shared_buffers ...

regards, tom lane

As part of my spinlock testing, I noticed that we test for __cpu__ when
using gcc, and __cpu when not using gcc. However, I see that my i386
gcc 2.95 defines both (shown using src/tools/ccsym):

__GNUC__=2
__GNUC_MINOR__=95
unix
__i386__
i386
__bsdi__
bsdi
__ELF__
__GAS__=2
__GAS_MINOR__=10
__unix__
__i386__
__i386__
__bsdi__
__bsdi__
__ELF__
__GAS__=2
__GAS_MINOR__=10
__unix
__i386
__bsdi
system=unix
system=bsd
cpu=i386
machine=i386
cpu=i386
machine=i386
i386
__i386
__i386__

So, I wonder if we should be testing _just_ for __cpu, perhaps starting
in 7.5.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian wrote:

Prompted by confusion over Itanium/Opterion, I have written a patch to
improve the way we define spinlocks for platforms and cpu's. It
basically decouples the OS from the CPU spinlock code. In almost all
cases, the spinlock code cares only about the compiler and CPU, not the
OS.

The patch:

o defines HAS_TEST_AND_SET inside each spinlock routine, not in
platform-specific files
o moves slock_t defines into the spinlock routines
o remove NEED_{CPU}_TAS_ASM define because it is no longer needed
o reports a compile error if spinlocks are not defined
o adds a configure option --without-spinlocks to allow
non-spinlock compiles

OK, we have to decide which parts of this patch we want added. I think
there was agreement that we want this part for 7.4:

o reports a compile error if spinlocks are not defined
o adds a configure option --without-spinlocks to allow
non-spinlock compiles

Now, do we also want to centralize the cpu tests in s_lock.h, or try to
patch up the include/port/*.h files for Opteron/Itanium. If you look in
freebsd.h, for example, you will see we basically try to duplicate the
cpu tests done in s_lock.h. To get this working, we would need to add
Itanium/Opteron tests there, and add i386 tests in other platforms that
previously supported only i386 and add Opteron/Itanium.

Or we could just apply the entire patch.

I am going to get some folks to test the patch today on a few platforms
to see how it works for them.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

On Fri, 12 Sep 2003, Tom Lane wrote:

"Marc G. Fournier" <scrappy@postgresql.org> writes:

If we force people to give a --without-spinlocks config option to build
that way, then `pg_config --configure' will reveal the dirty deed ...

That's not quite what I meant :) Right now, if I understood what Bruce
was saying, if someone doesn't have spinlocks, it switches to using SysV
Messenging, correct? In the current system, is there anything that one
can do on a running, live system, to detect that you aren't using
spinlocks?

It'll be fairly obvious if you use "ipcs -s" and count up the number of
semaphores created by the postmaster. Ordinarily we will grab
approximately max_connections semas, but without spinlocks it will
be somewhere north of max_connections + 2 * shared_buffers ...

'K, now, I know we acquire all our shared_buffers on startup now ... do we
do the same with semaphores? Or do they only grow as connections grow?
If we do acquire at the start, would it not be trivial to add a message to
the startup messages, based on #_of_semaphores != max_connections, that
tells ppl that spinlocks aren't being used?

Marc G. Fournier wrote:

On Fri, 12 Sep 2003, Tom Lane wrote:

"Marc G. Fournier" <scrappy@postgresql.org> writes:

If we force people to give a --without-spinlocks config option to build
that way, then `pg_config --configure' will reveal the dirty deed ...

That's not quite what I meant :) Right now, if I understood what Bruce
was saying, if someone doesn't have spinlocks, it switches to using SysV
Messenging, correct? In the current system, is there anything that one
can do on a running, live system, to detect that you aren't using
spinlocks?

It'll be fairly obvious if you use "ipcs -s" and count up the number of
semaphores created by the postmaster. Ordinarily we will grab
approximately max_connections semas, but without spinlocks it will
be somewhere north of max_connections + 2 * shared_buffers ...

'K, now, I know we acquire all our shared_buffers on startup now ... do we
do the same with semaphores? Or do they only grow as connections grow?
If we do acquire at the start, would it not be trivial to add a message to
the startup messages, based on #_of_semaphores != max_connections, that
tells ppl that spinlocks aren't being used?

But why not warn at compile time.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

"Marc G. Fournier" <scrappy@postgresql.org> writes:

'K, now, I know we acquire all our shared_buffers on startup now ... do we
do the same with semaphores?

Yes.

If we do acquire at the start, would it not be trivial to add a message to
the startup messages, based on #_of_semaphores != max_connections, that
tells ppl that spinlocks aren't being used?

The code already knows whether it's compiled to use spinlocks or not, it
hardly needs to test that way ;-). I thought you were asking how to
double-check a system that's live today.

I prefer Bruce's idea of a configure-time warning, myself.

regards, tom lane

--On Friday, September 12, 2003 09:53:10 -0400 Bruce Momjian
<pgman@candle.pha.pa.us> wrote:

As part of my spinlock testing, I noticed that we test for __cpu__ when
using gcc, and __cpu when not using gcc. However, I see that my i386
gcc 2.95 defines both (shown using src/tools/ccsym):

__GNUC__=2
__GNUC_MINOR__=95
unix
__i386__
i386
__bsdi__
bsdi
__ELF__
__GAS__=2
__GAS_MINOR__=10
__unix__
__i386__
__i386__
__bsdi__
__bsdi__
__ELF__
__GAS__=2
__GAS_MINOR__=10
__unix
__i386
__bsdi
system=unix
system=bsd
cpu=i386
machine=i386
cpu=i386
machine=i386
i386
__i386
__i386__

So, I wonder if we should be testing _just_ for __cpu, perhaps starting
in 7.5.

I corresponded with Dave Prosser of SCO, and he pointed me at the #assert
stuff. That's where the xxx=xxx stuff comes from.

Might it make more sense to use
#if #cpu(i386)
xxx
#endif

instead of depending on the different flavors of #defines.

GCC and at least SCO's cc support this.

I sent the details to Tom, since he seems to be the spinlock maintainer.

LER

--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749

Tom Lane wrote:

"Marc G. Fournier" <scrappy@postgresql.org> writes:

'K, now, I know we acquire all our shared_buffers on startup now ... do we
do the same with semaphores?

Yes.

If we do acquire at the start, would it not be trivial to add a message to
the startup messages, based on #_of_semaphores != max_connections, that
tells ppl that spinlocks aren't being used?

The code already knows whether it's compiled to use spinlocks or not, it
hardly needs to test that way ;-). I thought you were asking how to
double-check a system that's live today.

I prefer Bruce's idea of a configure-time warning, myself.

I talked to Marc via IM and I think he now understand the configure
error is best --- it is the most visible way to report the failure.
He was worried about packagers missing the warning, but it is a fatal
error and requires them to enable a flag, so it is pretty clear and
anyone who packages such a binary will know what they are doing.

He is uncomfortable with the port/*.h changes at this point, so it seems
I am going to have to add Itanium/Opteron tests to most of those files.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

He is uncomfortable with the port/*.h changes at this point, so it seems
I am going to have to add Itanium/Opteron tests to most of those files.

Why don't you try to put together a proposed patch of that kind, and
then we can look to see how big and ugly it is compared to the other?
If the alternative is shown to be really messy, that would sway my
opinion, maybe Marc's too.

regards, tom lane

Bruce Momjian <pgman@candle.pha.pa.us> writes:

As part of my spinlock testing, I noticed that we test for __cpu__ when
using gcc, and __cpu when not using gcc.
...
So, I wonder if we should be testing _just_ for __cpu, perhaps starting
in 7.5.

I might be all wet on this, but I had the idea that the __cpu__ forms
were considered more standard/common. In any case, I can't see any
good reason not to test for both. The amount of code saved by checking
only one is negligible; why should we take a chance on breaking things
for that?

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

As part of my spinlock testing, I noticed that we test for __cpu__ when
using gcc, and __cpu when not using gcc.
...
So, I wonder if we should be testing _just_ for __cpu, perhaps starting
in 7.5.

I might be all wet on this, but I had the idea that the __cpu__ forms
were considered more standard/common. In any case, I can't see any
good reason not to test for both. The amount of code saved by checking
only one is negligible; why should we take a chance on breaking things
for that?

Yes, that what confuses me --- which is standard. Right now, we aren't
consistent. My patch tests for __cpu__ on gcc, and both on non-gcc,
which seems safest.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

He is uncomfortable with the port/*.h changes at this point, so it seems
I am going to have to add Itanium/Opteron tests to most of those files.

Why don't you try to put together a proposed patch of that kind, and
then we can look to see how big and ugly it is compared to the other?
If the alternative is shown to be really messy, that would sway my
opinion, maybe Marc's too.

OK, here is an Opteron/Itanium patch that might work. I say "might"
because I don't have a lot of confidence in the current spinlock
detection code. There is an uncoupling between the definition of
HAS_TEST_AND_SET, the data type used by slock_t, and the assembler code.

For example, here is darwin.h:

#if defined(__ppc__)
#define HAS_TEST_AND_SET
#endif

#if defined(__ppc__)
typedef unsigned int slock_t;

#else
typedef unsigned char slock_t;

#endif

Does this say that Darwin on something other than PPC doesn't have
spinlocks? Is that going to hit a spinlock define, or fall through?

Also, look at NEED_I386_TAS_ASM: It is used only by SCO compilers,
though it is defined for all Intel platforms. The s_lock.h gcc test
already tests __i386__. It really doesn't do anything on non-SCO
compilers, and non-SCO compilers are better testing for i386 anyway.

Also, Solaris has just this:

#define HAS_TEST_AND_SET
typedef unsigned char slock_t;

How do they know what CPU is being used? Both Sparc and i386 use
"unsigned char", so I guess it is OK, but I think you can see what I
mean when I say I don't have a lot of confidence in what we have now.

Let me also add that some slock_t typedef's didn't match the assembly
code. For example, __alpha_ on netbsd.h had slock_t defined as
"unsigned long", while in linux.h it was "long int". I assumed the
alpha was the correct one, but clearly they should be the same because
they use the same assembly code.

See what I mean.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Does this say that Darwin on something other than PPC doesn't have
spinlocks? Is that going to hit a spinlock define, or fall through?

It says that darwin.h is broken, and always has been, for non-PPC
builds. Since there is no non-PPC Darwin (afaik), this is cosmetic.
Keep in mind that the argument here is exactly over whether we should
be fixing cosmetic issues right now.

Also, look at NEED_I386_TAS_ASM: It is used only by SCO compilers,
though it is defined for all Intel platforms. The s_lock.h gcc test
already tests __i386__. It really doesn't do anything on non-SCO
compilers, and non-SCO compilers are better testing for i386 anyway.

<shrug> Again, we were asking you what it would take to fix
Opteron/Itanium. Not to clean up cosmetic issues that have never caused
any problem before.

Let me also add that some slock_t typedef's didn't match the assembly
code. For example, __alpha_ on netbsd.h had slock_t defined as
"unsigned long", while in linux.h it was "long int". I assumed the
alpha was the correct one, but clearly they should be the same because
they use the same assembly code.

As long as it's the right width, whether the code thinks it's signed or
not isn't gonna matter. We don't do any comparisons on spinlocks,
except maybe zero/notzero.

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Does this say that Darwin on something other than PPC doesn't have
spinlocks? Is that going to hit a spinlock define, or fall through?

It says that darwin.h is broken, and always has been, for non-PPC
builds. Since there is no non-PPC Darwin (afaik), this is cosmetic.
Keep in mind that the argument here is exactly over whether we should
be fixing cosmetic issues right now.

Also, look at NEED_I386_TAS_ASM: It is used only by SCO compilers,
though it is defined for all Intel platforms. The s_lock.h gcc test
already tests __i386__. It really doesn't do anything on non-SCO
compilers, and non-SCO compilers are better testing for i386 anyway.

<shrug> Again, we were asking you what it would take to fix
Opteron/Itanium. Not to clean up cosmetic issues that have never caused
any problem before.

Let me also add that some slock_t typedef's didn't match the assembly
code. For example, __alpha_ on netbsd.h had slock_t defined as
"unsigned long", while in linux.h it was "long int". I assumed the
alpha was the correct one, but clearly they should be the same because
they use the same assembly code.

As long as it's the right width, whether the code thinks it's signed or
not isn't gonna matter. We don't do any comparisons on spinlocks,
except maybe zero/notzero.

My point is we don't know how many of these platforms are already using
non-spinlock code, but we will find out in 7.4, and we should find out
because those folks are getting poor performance.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

OK, here is an Opteron/Itanium patch that might work.

[having now read both patches]

Assuming that this covers the issues (what other OSes might run on
64-bit machines within 7.4's lifespan?) I think there is little question
that this is the more conservative patch to use for 7.4. I like your
larger cleanup, but for 7.5.

regards, tom lane

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

OK, here is an Opteron/Itanium patch that might work.

[having now read both patches]

Assuming that this covers the issues (what other OSes might run on
64-bit machines within 7.4's lifespan?) I think there is little question
that this is the more conservative patch to use for 7.4. I like your
larger cleanup, but for 7.5.

OK, all I am saying is that I can't 100% stand behind the partial patch.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian wrote:

Prompted by confusion over Itanium/Opterion, I have written a patch to
improve the way we define spinlocks for platforms and cpu's. It
basically decouples the OS from the CPU spinlock code. In almost all
cases, the spinlock code cares only about the compiler and CPU, not the
OS.

The patch:

o defines HAS_TEST_AND_SET inside each spinlock routine, not in
platform-specific files
o moves slock_t defines into the spinlock routines
o remove NEED_{CPU}_TAS_ASM define because it is no longer needed
o reports a compile error if spinlocks are not defined
o adds a configure option --without-spinlocks to allow
non-spinlock compiles

OK, this applied patch implements the last two items. The earlier items
will have to wait for 7.5.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian writes:

As part of my spinlock testing, I noticed that we test for __cpu__ when
using gcc, and __cpu when not using gcc. However, I see that my i386
gcc 2.95 defines both (shown using src/tools/ccsym):

gcc only documents the __foo__ version, so there is a small reason to lean
in that direction if you want to make it uniform.

--
Peter Eisentraut peter_e@gmx.net

Peter Eisentraut wrote:

Bruce Momjian writes:

As part of my spinlock testing, I noticed that we test for __cpu__ when
using gcc, and __cpu when not using gcc. However, I see that my i386
gcc 2.95 defines both (shown using src/tools/ccsym):

gcc only documents the __foo__ version, so there is a small reason to lean
in that direction if you want to make it uniform.

Oh, that helps, so my logic of testing for only __foo__ on gcc, and both
when the compiler isn't gcc or isn't known is correct.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian writes:

o adds a configure option --without-spinlocks to allow
non-spinlock compiles

--disable-spinlocks please.

--
Peter Eisentraut peter_e@gmx.net

Peter Eisentraut wrote:

Bruce Momjian writes:

o adds a configure option --without-spinlocks to allow
non-spinlock compiles

--disable-spinlocks please.

I can make the change, but --without seemed to more closely match
because it was like readline where you didn't have it, and had to say so
specifically. I don't see how we can say --disable because this is case
were we clearly don't have spinlocks to enable, no?

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian writes:

I can make the change, but --without seemed to more closely match
because it was like readline where you didn't have it, and had to say so
specifically. I don't see how we can say --disable because this is case
were we clearly don't have spinlocks to enable, no?

./configure --help | grep --relevant-stuff

Optional Features:
--disable-FEATURE do not include FEATURE (same as --enable-FEATURE=no)
--enable-FEATURE[=ARG] include FEATURE [ARG=yes]

Optional Packages:
--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]
--without-PACKAGE do not use PACKAGE (same as --with-PACKAGE=no)

Readline is a package, spinlocks are a feature.

--
Peter Eisentraut peter_e@gmx.net

Bruce Momjian wrote:

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

He is uncomfortable with the port/*.h changes at this point, so it seems
I am going to have to add Itanium/Opteron tests to most of those files.

Why don't you try to put together a proposed patch of that kind, and
then we can look to see how big and ugly it is compared to the other?
If the alternative is shown to be really messy, that would sway my
opinion, maybe Marc's too.

OK, here is an Opteron/Itanium patch that might work. I say "might"
because I don't have a lot of confidence in the current spinlock
detection code. There is an uncoupling between the definition of
HAS_TEST_AND_SET, the data type used by slock_t, and the assembler code.

Is the Itanium tas implementation correct? I think it should be
xchg4.aqv instead of just xchg4 - as far as I know a normal atomic
exchange is is not a memory barrier on Itanium. At least the Linux
kernel version contains "cmpxchg4.aqv".

--
Manfred

Manfred Spraul wrote:

Is the Itanium tas implementation correct? I think it should be
xchg4.aqv instead of just xchg4 - as far as I know a normal atomic
exchange is is not a memory barrier on Itanium. At least the Linux
kernel version contains "cmpxchg4.aqv".

Sorry for the noise, I'm wrong:
Itanium automatically uses acquire semantics with xchg.
See top of page 16 on
http://h21007.www2.hp.com/dspp/files/unprotected/itanium/spinlocks.pdf

--
Manfred

OK. You'da boss. :-)

---------------------------------------------------------------------------

Peter Eisentraut wrote:

Bruce Momjian writes:

I can make the change, but --without seemed to more closely match
because it was like readline where you didn't have it, and had to say so
specifically. I don't see how we can say --disable because this is case
were we clearly don't have spinlocks to enable, no?

./configure --help | grep --relevant-stuff

Optional Features:
--disable-FEATURE do not include FEATURE (same as --enable-FEATURE=no)
--enable-FEATURE[=ARG] include FEATURE [ARG=yes]

Optional Packages:
--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]
--without-PACKAGE do not use PACKAGE (same as --with-PACKAGE=no)

Readline is a package, spinlocks are a feature.

--
Peter Eisentraut peter_e@gmx.net

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Manfred Spraul <manfred@colorfullife.com> writes:

Is the Itanium tas implementation correct?

FWIW, this evening I did a few dozen iterations of "make check" parallel
regression tests on a 4-way Itanium box at Red Hat's Toronto office,
working from CVS-tip sources. No sign of problems. That's not a proof
of correctness, of course, but it does give me some confidence ...

regards, tom lane

On Fri, 12 Sep 2003, Bruce Momjian wrote:

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

OK, here is an Opteron/Itanium patch that might work.

[having now read both patches]

Assuming that this covers the issues (what other OSes might run on
64-bit machines within 7.4's lifespan?) I think there is little question
that this is the more conservative patch to use for 7.4. I like your
larger cleanup, but for 7.5.

OK, all I am saying is that I can't 100% stand behind the partial patch.

S'alright, but the partial patch is better then what we have now, which is
what we're after ...

Done.

---------------------------------------------------------------------------

Peter Eisentraut wrote:

Bruce Momjian writes:

I can make the change, but --without seemed to more closely match
because it was like readline where you didn't have it, and had to say so
specifically. I don't see how we can say --disable because this is case
were we clearly don't have spinlocks to enable, no?

./configure --help | grep --relevant-stuff

Optional Features:
--disable-FEATURE do not include FEATURE (same as --enable-FEATURE=no)
--enable-FEATURE[=ARG] include FEATURE [ARG=yes]

Optional Packages:
--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]
--without-PACKAGE do not use PACKAGE (same as --with-PACKAGE=no)

Readline is a package, spinlocks are a feature.

--
Peter Eisentraut peter_e@gmx.net

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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073