Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?

Michael Paquier <michael@paquier.xyz>

From: Michael Paquier <michael@paquier.xyz>

To: Lukas Fittl <lukas@fittl.com>

Cc: Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>, David Geier <geidav.pg@gmail.com>, Pavel Stehule <pavel.stehule@gmail.com>, vignesh C <vignesh21@gmail.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Maciek Sakrejda <m.sakrejda@gmail.com>, Tomas Vondra <tomas@vondra.me>

Date: 2025-07-28T06:38:20Z

Lists: pgsql-hackers

Commits

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pg_test_timing: Also test RDTSC[P] timing, report time source, TSC frequency
- 16fca4825483 19 (unreleased) landed
Allow retrieving x86 TSC frequency/flags from CPUID
- bcb2cf41f964 19 (unreleased) landed
instrumentation: Standardize ticks to nanosecond conversion method
- 0022622c93d9 19 (unreleased) landed
instrumentation: Use Time-Stamp Counter on x86-64 to lower overhead
- 294520c44487 19 (unreleased) landed
Zero initialize uses of instr_time about to trigger compiler warnings
- 25b2aba0c3a5 16.0 landed
instr_time: Represent time as an int64 on all platforms
- 03023a2664f8 16.0 landed
Add 250c8ee07ed to git-blame-ignore-revs
- ff23b592ad66 16.0 cited

On Sun, Jul 27, 2025 at 12:50:54PM -0700, Lukas Fittl wrote:
> 0001 - Improve the __cpuidex check added for a different purpose
> in 792752af4eb5 to:
> 
> - Fix a typo (configure was incorrectly checking for "__get_cpuidex", vs
> meson.build was doing it correctly)

It seems to me that this is an independent issue that had better be
backpatched down to where this configure check has been introduced,
no?

> - Adds support for non-MSVC compilers as well (e.g. GCC 11+), where
> __cpuidex is defined in cpuid.h, not intrin.h

This one should be a HEAD-only change.
--
Michael