BUG #8531: systemtap probe mark(checkpoint__done) error when i read the parameters

digoal@126.com wrote:

When i probe checkpoint__done, and read the parameters , it's error:

CHECKPOINT_DONE doesn't have parameters. It works for CHECKPOINT_START
because that one has one parameter.

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HI,

But the CHECKPOINT_DONE used in src have parameters:
CheckpointStats.ckpt_bufs_written,
NBuffers,
CheckpointStats.ckpt_segs_added,
CheckpointStats.ckpt_segs_removed,
CheckpointStats.ckpt_segs_recycled

probes.h
/* TRACE_POSTGRESQL_CHECKPOINT_DONE ( int, int, int, int, int) */
#if defined STAP_SDT_V1
#define TRACE_POSTGRESQL_CHECKPOINT_DONE_ENABLED() __builtin_expect (checkpoint__done_semaphore, 0)
#define postgresql_checkpoint__done_semaphore checkpoint__done_semaphore
#else
#define TRACE_POSTGRESQL_CHECKPOINT_DONE_ENABLED() __builtin_expect (postgresql_checkpoint__done_semaphore, 0)
#endif
__extension__ extern unsigned short postgresql_checkpoint__done_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
#define TRACE_POSTGRESQL_CHECKPOINT_DONE(arg1,arg2,arg3,arg4,arg5) \
DTRACE_PROBE5(postgresql,checkpoint__done,arg1,arg2,arg3,arg4,arg5)

src/backend/access/transam/xlog.c
TRACE_POSTGRESQL_CHECKPOINT_DONE(CheckpointStats.ckpt_bufs_written,
NBuffers,
CheckpointStats.ckpt_segs_added,
CheckpointStats.ckpt_segs_removed,
CheckpointStats.ckpt_segs_recycled);

and PostgreSQL Document:

| checkpoint-done | (int, int, int, int, int) | Probe that fires when a checkpoint is complete. (The probes listed next fire in sequence during checkpoint processing.) arg0 is the number of buffers written. arg1 is the total number of buffers. arg2, arg3 and arg4 contain the number of xlog file(s) added, removed and recycled respectively. |

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At 2013-10-17 23:47:54,"Alvaro Herrera" <alvherre@2ndquadrant.com> wrote:

digoal wrote:

But the CHECKPOINT_DONE used in src have parameters:
CheckpointStats.ckpt_bufs_written,
NBuffers,
CheckpointStats.ckpt_segs_added,
CheckpointStats.ckpt_segs_removed,
CheckpointStats.ckpt_segs_recycled

Uh, you're right. I confused it with BUFFER_CHECKPOINT_DONE.

I have no useful answer for this right now. The types of the parameters
appear correct, but that's as further as I checked.

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HI,
I use the two method below get values from probes it.

int v1,v2,v3,v4,vnb;
vnb =NBuffers;
v1 =CheckpointStats.ckpt_bufs_written;
v2 =CheckpointStats.ckpt_segs_added;
v3 =CheckpointStats.ckpt_segs_removed;
v4 =CheckpointStats.ckpt_segs_recycled;

TRACE_POSTGRESQL_CHECKPOINT_DONE(v1,
vnb,
v2,
v3,
v4);

this method cann't output the NBuffers value.
[root@db-172-16-3-150~]# stap -D MAXSTRINGLEN=100000 --vp 10000 -e 'probe process("/home/pg93/pgsql9.3.1/bin/postgres").mark("checkpoint__done") {println($$locals$$)}'
Pass 1: parsed user script and 96 library script(s) using 152048virt/25252res/2116shr/23956data kb, in 230usr/10sys/252real ms.
shutdown=? checkPoint={.redo=26648020808, .ThisTimeLineID=1, .PrevTimeLineID=1, .fullPageWrites='\001', .nextXidEpoch=0, .nextXid=130667532, .nextOid=57479, .nextMulti=1, .nextMultiOffset=0, .oldestXid=1800, .oldestXidDB=1, .oldestMulti=1, .oldestMultiDB=1, .time=1382057407, .oldestActiveXid=130667532} recptr=26648020968 Insert={.PrevRecord=26648020864, .curridx=886, .currpage=0x7f6ca01fc000, .currpos="", .RedoRecPtr=26648020808, .forcePageWrites='\000', .fullPageWrites='\001', .exclusiveBackup='\000', .nonExclusiveBackups=0, .lastBackupStart=0} rdata={.data="H?X4", .len=72, .buffer=0, .buffer_std='\001', .next=0x0} freespace=? _logSegNo=? vxids={.backendId=?, .localTransactionId=?} nvxids=0 __func__="CreateCheckPoint" v1=0 v2=0 v3=0 v4=0 vnb=?

the second method:
[root@db-172-16-3-150~]# stap -D MAXSTRINGLEN=100000 --vp 10000 -e '
probe process("/home/pg93/pgsql9.3.1/bin/postgres").mark("checkpoint__done") {
printf("ckpt_bufs_written:%d, ckpt_segs_added:%d, ckpt_segs_removed:%d, ckpt_segs_recycled:%d, NBuffers:%d\n", @var("CheckpointStats")->ckpt_bufs_written, @var("CheckpointStats")->ckpt_segs_added, @var("CheckpointStats")->ckpt_segs_removed, @var("CheckpointStats")->ckpt_segs_recycled, @var("NBuffers"))
}'
Pass 1: parsed user script and 96 library script(s) using 151984virt/25256res/2116shr/23892data kb, in 240usr/20sys/251real ms.
ckpt_bufs_written:0, ckpt_segs_added:0, ckpt_segs_removed:0, ckpt_segs_recycled:0, NBuffers:262144
ckpt_bufs_written:0, ckpt_segs_added:0, ckpt_segs_removed:0, ckpt_segs_recycled:0, NBuffers:262144

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公益是一辈子的事,I'm Digoal,Just Do It.

At 2013-10-17 23:47:54,"Alvaro Herrera" <alvherre@2ndquadrant.com> wrote:

Alvaro Herrera <alvherre@2ndquadrant.com> writes:

digoal wrote:

But the CHECKPOINT_DONE used in src have parameters:
CheckpointStats.ckpt_bufs_written,
NBuffers,
CheckpointStats.ckpt_segs_added,
CheckpointStats.ckpt_segs_removed,
CheckpointStats.ckpt_segs_recycled

Uh, you're right. I confused it with BUFFER_CHECKPOINT_DONE.

I have no useful answer for this right now. The types of the parameters
appear correct, but that's as further as I checked.

FWIW, I'd guess this is a bug in systemtap, and accordingly should be
reported to those folk. Try filing at bugzilla.redhat.com ... although
they might tell you to try a supported systemtap release, which yours
isn't AFAICT. What I see on my RHEL6 box is systemtap-1.8-7.el6.x86_64
and stap -V sez

Systemtap translator/driver (version 1.8/0.152 non-git sources)
Copyright (C) 2005-2012 Red Hat, Inc. and others
This is free software; see the source for copying conditions.
enabled features: AVAHI LIBRPM LIBSQLITE3 NSS TR1_UNORDERED_MAP NLS

regards, tom lane

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HI,
Thanks tom lane.
The stap 2.4 version has same problem, I need use @var("varname") get the value instead $argN.

[root@db-172-16-3-150 ~]# stap -V
Systemtap translator/driver (version 2.4/0.152, commit release-2.3-133-g335e342 + changes)
Copyright (C) 2005-2013 Red Hat, Inc. and others
This is free software; see the source for copying conditions.
enabled features: LIBSQLITE3 BOOST_SHARED_PTR TR1_UNORDERED_MAP NLS JAVA
[root@db-172-16-3-150 ~]# which stap
/opt/systemtap/bin/stap
[root@db-172-16-3-150 ~]# stap --vp 11111 -e '

probe process("/home/pg93/pgsql9.3.1/bin/postgres").mark("checkpoint__done") {
println($$vars)
exit()
}'

Pass 1: parsed user script and 96 library script(s) using 152024virt/25212res/2104shr/23932data kb, in 240usr/10sys/253real ms.
WARNING: Can't parse SDT_V3 operand 'CheckpointStats+40(%rip)': identifier '$$vars' at <input>:3:11
source: println($$vars)
^
WARNING: Can't parse SDT_V3 operand 'NBuffers(%rip)': identifier '$$vars' at :3:11
source: println($$vars)
^
WARNING: Can't parse SDT_V3 operand 'CheckpointStats+44(%rip)': identifier '$$vars' at :3:11
source: println($$vars)
^
WARNING: Can't parse SDT_V3 operand 'CheckpointStats+48(%rip)': identifier '$$vars' at :3:11
source: println($$vars)
^
WARNING: Can't parse SDT_V3 operand 'CheckpointStats+52(%rip)': identifier '$$vars' at :3:11
source: println($$vars)
^
semantic error: unable to find local 'arg1', [man error::dwarf] dieoffset 0xd00f5 in /home/pg93/pgsql9.3.1/bin/postgres, near pc 0x4b9789 in CreateCheckPoint xlog.c (alternatives: $flags $shutdown $checkPoint $recptr $Insert $rdata $freespace $_logSegNo $vxids $nvxids $__func__): identifier '$$vars' at :3:11
source: println($$vars)
^

semantic error: SDT asm not understood, requires debuginfo: identifier '$$vars' at :3:11
source: println($$vars)
^

Pass 2: analyzed script: 1 probe(s), 1 function(s), 0 embed(s), 0 global(s) using 176172virt/32892res/5620shr/27852data kb, in 30usr/10sys/151real ms.
Pass 2: analysis failed. [man error::pass2]

Use @var("varname") can get the value correct.
[root@db-172-16-3-150 ~]# stap --vp 11111 -e '
probe process("/home/pg93/pgsql9.3.1/bin/postgres").mark("checkpoint__done") {
println(@var("NBuffers"))
exit()
}'
Pass 1: parsed user script and 96 library script(s) using 152024virt/25212res/2104shr/23932data kb, in 240usr/20sys/254real ms.
Pass 2: analyzed script: 1 probe(s), 2 function(s), 0 embed(s), 0 global(s) using 175644virt/32208res/5524shr/27324data kb, in 30usr/0sys/36real ms.
Pass 3: translated to C into "/tmp/stap9yW3g4/stap_4e8bb94e54f595ef6f3e48aed9859200_1792_src.c" using 303812virt/32556res/5872shr/27324data kb, in 20usr/100sys/109real ms.
Pass 4: compiled C into "stap_4e8bb94e54f595ef6f3e48aed9859200_1792.ko" in 2290usr/410sys/2699real ms.
Pass 5: starting run.
2621440
Pass 5: run completed in 0usr/30sys/11089real ms.

--
公益是一辈子的事,I'm Digoal,Just Do It.

At 2013-11-11 05:54:50,"Tom Lane" <tgl@sss.pgh.pa.us> wrote: