CPU

On Monday 03 December 2007, Tom Allison wrote:

is there much of a difference in performance between a XEON, dual
core from intel and a dual core AMD 64 CPU?

I need a bit of an upgrade and am not sure which, if any, have a
significant advantage for postgres databases.

Personally I've never seen postgresql suck majorly on CPU performance. I guess
the biggest speed increase lies in ultra fast I/O, i.e. high spinning disks
and battery backed hardware RAID. Databases tend to suck more on I/O than
processor unless you do a lot fo sorting, distinct selects etc.
Multi or single processor is just a matter of how many clients connect. AFAIK
postgresql is not really multi-threaded, but runs each connection (master
process) on one processor at a time. So if you have a quad core (or 4
processor machine), you'll have 4 postmasters "processing" any given time -
the bottleneck again is I/O because usually all processors share the same
ressources (memory and disks).

So basically I would invest in fast I/O and would care less about the
processors. More memory at hand may also be beneficial.

U.C.

Uwe C. Schroeder wrote:

On Monday 03 December 2007, Tom Allison wrote:

is there much of a difference in performance between a XEON, dual
core from intel and a dual core AMD 64 CPU?

Well honestly, with how cheap you can get a quad core from Intel... I
say do that :). The general difference between a dual core opteron and a
dual core xeon will likely not be noticeable to a PostgreSQL
installation (generally speaking).

However, the two extra cores (even if slower), will greatly help if you
have any kind of concurrency.

Sincerely,

Joshua D. Drake

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On 12/03/07 21:27, Joshua D. Drake wrote:

Uwe C. Schroeder wrote:

On Monday 03 December 2007, Tom Allison wrote:

is there much of a difference in performance between a XEON, dual
core from intel and a dual core AMD 64 CPU?

Well honestly, with how cheap you can get a quad core from Intel... I
say do that :). The general difference between a dual core opteron and a
dual core xeon will likely not be noticeable to a PostgreSQL
installation (generally speaking).

However, the two extra cores (even if slower), will greatly help if you
have any kind of concurrency.

Are there any heat/power considerations? An Opteron will most
likely draw less power, generate less heat, be easier to cool and
thus generate less noise.

Of course, the heat and whine from those 10K and 15K SCSI drives
will override any possible Opteron CPU fan quietness.

- --
Ron Johnson, Jr.
Jefferson LA USA

%SYSTEM-F-FISH, my hovercraft is full of eels
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On Mon, 03 Dec 2007 22:30:58 -0600
Ron Johnson <ron.l.johnson@cox.net> wrote:

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On 12/03/07 21:27, Joshua D. Drake wrote:

Uwe C. Schroeder wrote:

On Monday 03 December 2007, Tom Allison wrote:

is there much of a difference in performance between a XEON, dual
core from intel and a dual core AMD 64 CPU?

Well honestly, with how cheap you can get a quad core from Intel...
I say do that :). The general difference between a dual core
opteron and a dual core xeon will likely not be noticeable to a
PostgreSQL installation (generally speaking).

However, the two extra cores (even if slower), will greatly help if
you have any kind of concurrency.

Are there any heat/power considerations? An Opteron will most
likely draw less power, generate less heat, be easier to cool and
thus generate less noise.

Its a server... why are we worried about noise? Heat... well yes but
what you say below :)

Of course, the heat and whine from those 10K and 15K SCSI drives
will override any possible Opteron CPU fan quietness.

- --
Ron Johnson, Jr.
Jefferson LA USA

%SYSTEM-F-FISH, my hovercraft is full of eels
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---------------------------(end of
broadcast)--------------------------- TIP 6: explain analyze is your
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On Mon, 3 Dec 2007, Joshua D. Drake wrote:

Well honestly, with how cheap you can get a quad core from Intel... I
say do that

Exactly, the budget single processor configuration to beat in server land
right now is the Xeon X3210. The frequency of the cores is a little on
the low side, so individual queries won't run quite as fast as some of the
dual-core alternatives, but when you get twice as many of them it's hard
to complain. The X3220 is a little faster and more expensive.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD

Josh,

However, the two extra cores (even if slower), will greatly help if you

have any kind of concurrency.

as much as I understand with running Postgres in the default configuration,
there *will* be concurrency, without an "if" ?

I am thinking of the background writer, the autovacuum process, the log
writer and finally the connection serving process. ... quite sure of that
"default concurrency" because I had to explain those basic 5 postgres.exe to
at least 8 Windows Admins...

My non-benchmarked experience is that "multicore and postgres good"
(experience mainly drawn from windows)

Harald

--
GHUM Harald Massa
persuadere et programmare
Harald Armin Massa
Spielberger Straße 49
70435 Stuttgart
0173/9409607
fx 01212-5-13695179
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