| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | David Geier <geidav(dot)pg(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Lukas Fittl <lukas(at)fittl(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(at)postgresql(dot)org |
| Subject: | Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc? |
| Date: | 2023-01-23 20:30:06 |
| Message-ID: | 20230123203006.qgqhtxh447qoj4yr@awork3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
On 2023-01-23 18:52:44 +0100, David Geier wrote:
> One thing I was wondering about: why did you chose to use a signed instead
> of an unsigned 64-bit integer for the ticks?
That's been the case since my first post in the thread :). Mainly, it seems
easier to detect underflow cases during subtraction that way. And the factor
of 2 in range doesn't change a whole lot.
> > > 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.
> >
> > 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...
> I'll include them in my new patch set and also have a careful look at them.
Thanks.
Greetings,
Andres Freund
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