Horton

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

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: "Andrey M. Borodin" <x4mmm@yandex-team.ru>, Hannu Krosing <hannuk@google.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2024-06-19T15:44:45Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Force LC_NUMERIC to C while running TAP tests.

  2. Minor tweaks for pg_test_timing.

  3. Change pg_test_timing to measure in nanoseconds not microseconds.

On 18.06.24 07:47, Andrey M. Borodin wrote:
> 
> 
>> On 19 Mar 2024, at 13:28, Peter Eisentraut <peter@eisentraut.org> wrote:
>>
>> I feel that we don't actually have any information about this portability concern.  Does anyone know what precision we can expect from gettimeofday()?  Can we expect the full microsecond precision usually?
> 
> At PGConf.dev Hannu Krossing draw attention to pg_test_timing module. I’ve tried this module(slightly modified to measure nanoseconds) on some systems, and everywhere I found ~100ns resolution (95% of ticks fall into 64ns and 128ns buckets).

AFAICT, pg_test_timing doesn't use gettimeofday(), so this doesn't 
really address the original question.