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help / color / mirror / Atom feedFrom: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: David Geier <geidav.pg@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>
Cc: Lukas Fittl <lukas@fittl.com>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Ibrar Ahmed <ibrar.ahmad@gmail.com>
Cc: Maciek Sakrejda <m.sakrejda@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?
Date: Fri, 13 Jan 2023 15:25:16 -0500
Message-ID: <294643.1673641516@sss.pgh.pa.us> (raw)
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Andres Freund <andres@anarazel.de> writes:
> On 2023-01-04 13:02:05 +0100, David Geier wrote:
>> Subject: [PATCH 1/3] Change instr_time to just store nanoseconds, that's
>> cheaper.
> Does anybody see a reason to not move forward with this aspect? We do a fair
> amount of INSTR_TIME_ACCUM_DIFF() etc, and that gets a good bit cheaper by
> just using nanoseconds.
Cheaper, and perhaps more accurate too? Don't recall if we have any code
paths where the input timestamps are likely to be better-than-microsecond,
but surely that's coming someday.
I'm unsure that we want to deal with rdtsc's vagaries in general, but
no objection to changing instr_time.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, andres@anarazel.de, geidav.pg@gmail.com, vignesh21@gmail.com, lukas@fittl.com, michael@paquier.xyz, ibrar.ahmad@gmail.com, m.sakrejda@gmail.com
Subject: Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?
In-Reply-To: <294643.1673641516@sss.pgh.pa.us>
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