Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?

From: Lukas Fittl <lukas(at)fittl(dot)com>
To: John Naylor <johncnaylorls(at)gmail(dot)com>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>, Hannu Krosing <hannuk(at)google(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, Maciek Sakrejda <m(dot)sakrejda(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, David Geier <geidav(dot)pg(at)gmail(dot)com>
Subject: Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?
Date: 2026-04-06 01:47:51
Message-ID: CAP53Pky0ASnA1CX6Sxbe43oDYzeyAw6_suC9tu9UuZkedP+KBg@mail.gmail.com
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On Sat, Apr 4, 2026 at 7:29 PM John Naylor <johncnaylorls(at)gmail(dot)com> wrote:
> v18-0002 looks good to me as far as feature-detection, but aside from
> that there are plenty of domain-specific details that I lack the means
> to check on short notice. I did verify that OSXSAVE support is still
> functional.

Thanks for your input and reviews!

Attached v19 rebased over the instrument.c changes in 5a79e78501f4,
and also a slight adjustment to the commit message in 0001 to mention
the inverse pg_ns_to_ticks() function that was added for
INSTR_TIME_ADD_NANOSEC. No other changes.

Thanks,
Lukas

--
Lukas Fittl

Attachment Content-Type Size
v19-0004-pg_test_timing-Also-test-RDTSC-RDTSCP-timing-and.patch application/octet-stream 7.3 KB
v19-0001-instrumentation-Streamline-ticks-to-nanosecond-c.patch application/octet-stream 16.4 KB
v19-0005-instrumentation-ARM-support-for-fast-time-measur.patch application/octet-stream 8.4 KB
v19-0003-instrumentation-Use-Time-Stamp-Counter-TSC-on-x8.patch application/octet-stream 30.8 KB
v19-0002-Allow-retrieving-x86-TSC-frequency-flags-from-CP.patch application/octet-stream 6.6 KB

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