Re: What is a typical precision of gettimeofday()?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>
Cc: Hannu Krosing <hannuk(at)google(dot)com>, Peter Eisentraut <peter(at)eisentraut(dot)org>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: What is a typical precision of gettimeofday()?
Date: 2025-07-08 19:29:48
Message-ID: 900154.1752002988@sss.pgh.pa.us
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Andrey Borodin <x4mmm(at)yandex-team(dot)ru> writes:
>> On 8 Jul 2025, at 23:07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> The fact that the clock tick is about 40ns is extremely
>> obvious in this presentation.

> FWIW while working on UUID v7 Masahiko found that if we try to read real time with clock_gettime(CLOCK_REALTIME,) measurement is truncated to microseconds.

Yeah. Bear in mind that instr_time.h uses CLOCK_MONOTONIC_RAW on
macOS, so that's what we're looking at here.

regards, tom lane

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