Re: [PATCH] Identify LWLocks in tracepoints

Peter Eisentraut <peter.eisentraut@enterprisedb.com>

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From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>

To: Craig Ringer <craig.ringer@enterprisedb.com>

Cc: pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2021-04-29T07:31:54Z

Lists: pgsql-hackers

Attachments

0001-Prevent-lwlock-dtrace-probes-from-unnecessary-work.patch (text/plain) patch 0001

On 14.04.21 15:20, Peter Eisentraut wrote:
> On 12.04.21 07:46, Craig Ringer wrote:
>>      > To use systemtap semaphores (the _ENABLED macros) you need to run
>>     dtrace
>>      > -g to generate a probes.o then link that into postgres.
>>      >
>>      > I don't think we do that. I'll double check soon.
>>
>>     We do that.  (It's -G.)
>>
>>
>> Huh. I could've sworn we didn't. My mistake, it's there in 
>> src/backend/Makefile .
>>
>> In that case I'll amend the patch to use semaphore guards.
> 
> This whole thread is now obviously moved to consideration for PG15, but 
> I did add an open item about this particular issue 
> (https://wiki.postgresql.org/wiki/PostgreSQL_14_Open_Items, search for 
> "dtrace").  So if you could produce a separate patch that adds the 
> _ENABLED guards targeting PG14 (and PG13), that would be helpful.

Here is a proposed patch for this.

Commits

Emit dummy statements for probes.d probes when disabled
- 0d204a4b09f7 13.3 landed
- fa8fbadb934b 14.0 landed
Prevent lwlock dtrace probes from unnecessary work
- e48ce7ef0ef8 13.3 landed
- b94409a02f61 14.0 landed
doc: Fix typo in logicaldecoding.sgml.
- 5fe83adad9ef 14.0 cited
Move lwlock-release probe back where it belongs
- 96ae658e6238 14.0 landed
Remove bogus tracepoint
- 09418bed67a7 14.0 landed
Simplify LWLock tranche machinery by removing array_base/array_stride.
- 3761fe3c20bb 10.0 cited
Improve LWLock scalability.
- ab5194e6f617 9.5.0 cited