Horton

Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: David Geier <geidav.pg@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, David Geier <geidav.pg@gmail.com>, vignesh C <vignesh21@gmail.com>, Lukas Fittl <lukas@fittl.com>, Michael Paquier <michael@paquier.xyz>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Maciek Sakrejda <m.sakrejda@gmail.com>, pgsql-hackers@postgresql.org
Date: 2023-01-21T05:31:57Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. pg_test_timing: Also test RDTSC[P] timing, report time source, TSC frequency

  2. Allow retrieving x86 TSC frequency/flags from CPUID

  3. instrumentation: Standardize ticks to nanosecond conversion method

  4. instrumentation: Use Time-Stamp Counter on x86-64 to lower overhead

  5. Zero initialize uses of instr_time about to trigger compiler warnings

  6. instr_time: Represent time as an int64 on all platforms

  7. Add 250c8ee07ed to git-blame-ignore-revs

Attachments

Hi,

On 2023-01-20 20:16:13 -0800, Andres Freund wrote:
> On 2023-01-18 14:05:35 +0100, David Geier wrote:
> > @Andres: will you take care of these changes and provide me with an updated
> > patch set so I can rebase the RDTSC changes?
> > Otherwise, I can also apply Tom suggestions to your patch set and send out
> > the complete patch set.
> 
> I'm planning to push most of my changes soon, had hoped to get to it a bit
> sooner, but ...

I pushed the int64-ification commits.


> If you have time to look at the pg_test_timing part, it'd be
> appreciated. That's a it larger, and nobody looked at it yet. So I'm a bit
> hesitant to push it.

I haven't yet pushed the pg_test_timing (nor it's small prerequisite)
patch.

Thanks to Justin I've polished the pg_test_timing docs some.


I've attached those two patches. Feel free to include them in your series if
you want, then the CF entry (and thus cfbot) makes sense again...

Greetings,

Andres Freund