Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?

Lukas Fittl <lukas@fittl.com>

From: Lukas Fittl <lukas@fittl.com>

To: David Geier <geidav.pg@gmail.com>, Andres Freund <andres@anarazel.de>

Cc: Hannu Krosing <hannuk@google.com>, Robert Haas <robertmhaas@gmail.com>, Pavel Stehule <pavel.stehule@gmail.com>, vignesh C <vignesh21@gmail.com>, Michael Paquier <michael@paquier.xyz>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Maciek Sakrejda <m.sakrejda@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2026-02-01T03:14:56Z

Lists: pgsql-hackers

Attachments

v5-0001-Check-for-HAVE__CPUIDEX-and-HAVE__GET_CPUID_COUNT.patch (application/x-patch) patch v5-0001
v5-0002-Use-time-stamp-counter-to-measure-time-on-Linux-x.patch (application/x-patch) patch v5-0002
v5-0003-pg_test_timing-Also-test-fast-timing-and-report-t.patch (application/x-patch) patch v5-0003

On Sat, Jan 31, 2026 at 12:11 PM Lukas Fittl <lukas@fittl.com> wrote:
> I've reworked the patch a bit more, see attached v4

And of course, I took the wrong branch when running "git format-patch"
- apologies.

See attached v5.


Thanks,
Lukas

--
Lukas Fittl

Commits

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pg_test_timing: Show additional TSC clock source debug info
- 5ba34f6dc838 19 (unreleased) landed
instrumentation: Avoid CPUID 0x15/0x16 for Hypervisor TSC frequency
- 7fc36c5db550 19 (unreleased) landed
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
Check for __cpuidex and __get_cpuid_count separately
- effaa464afd3 19 (unreleased) landed
pg_test_timing: Reduce per-loop overhead
- 82c0cb4e672d 19 (unreleased) landed
Refactor handling of x86 CPUID instructions
- be6a7494d2e3 19 (unreleased) landed
instrumentation: Drop INSTR_TIME_SET_CURRENT_LAZY macro
- 9d6294c09ed0 19 (unreleased) landed
Rename pg_crc32c_sse42_choose.c for general purpose
- b9278871f991 19 (unreleased) cited
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