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| author | Thomas Munro <tmunro@postgresql.org> | 2023-03-15 16:14:36 +1300 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2023-03-15 17:23:02 +1300 |
| commit | e4da2a44c17a36904d4d083f9a96e90041d28f76 (patch) | |
| tree | 53b3a9f57fccb29c4da3248f1ff48470d908c668 /src/port | |
| parent | 805b821e77a3a7d8d7827711e82e87c7bf61c681 (diff) | |
| download | postgresql-e4da2a44c17a36904d4d083f9a96e90041d28f76.tar.gz | |
Update obsolete comment about pg_usleep() accuracy.
There are still some systems that use traditional tick-based sleep
timing, but many including Linux, FreeBSD and macOS started using high
resolution timer hardware more directly a decade or two ago. Update our
comment about that. Also highlight that Windows is like the older
Unixen in that respect.
Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKG%2BogAon8_V223Ldv6taPR2uKH3X_UJ_A7LJAf3-VRARPA%40mail.gmail.com
Diffstat (limited to 'src/port')
| -rw-r--r-- | src/port/pgsleep.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/src/port/pgsleep.c b/src/port/pgsleep.c index 8a709cd01d..b34efeae8c 100644 --- a/src/port/pgsleep.c +++ b/src/port/pgsleep.c @@ -25,9 +25,10 @@ /* * pg_usleep --- delay the specified number of microseconds. * - * NOTE: although the delay is specified in microseconds, the effective - * resolution is only 1/HZ, or 10 milliseconds, on most Unixen. Expect - * the requested delay to be rounded up to the next resolution boundary. + * NOTE: Although the delay is specified in microseconds, older Unixen and + * Windows use periodic kernel ticks to wake up, which might increase the delay + * time significantly. We've observed delay increases as large as 20 + * milliseconds on supported platforms. * * On machines where "long" is 32 bits, the maximum delay is ~2000 seconds. * |