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From: Tom Lane <[email protected]>
To: Hannu Krosing <[email protected]>
Cc: Peter Eisentraut <[email protected]>
Cc: Andrey M. Borodin <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: What is a typical precision of gettimeofday()?
Date: Tue, 02 Jul 2024 13:50:13 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAMT0RQTzzzSfO4j3PeF5riQ_mER_9BE_LNnjEUrM349ZhhDbww@mail.gmail.com>
References: <[email protected]>
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Hannu Krosing <[email protected]> writes:
> Also, reading directly in ticks on M1 gave "loop time including
> overhead: 2.13 ns" (attached code works on Clang, not sure about GCC)

I don't think we should mess with that, given the portability
problems you mentioned upthread.

> I'll also take a look at the docs and try to propose something

OK.

> Do we also need tests for this one ?

Yeah, it was annoying me that we are eating the overhead of a TAP test
for pg_test_timing and yet it covers barely a third of the code [1].
We obviously can't expect any specific numbers out of a test, but I
was contemplating running "pg_test_timing -d 1" and just checking for
(a) zero exit code and (b) the expected header lines in the output.

			regards, tom lane

[1] https://coverage.postgresql.org/src/bin/pg_test_timing/pg_test_timing.c.gcov.html

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