[nginx] Removed CLOCK_MONOTONIC_COARSE support.

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/9e7de0547f09
branches:  
changeset: 7939:9e7de0547f09
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Thu Oct 21 18:38:38 2021 +0300
description:
Removed CLOCK_MONOTONIC_COARSE support.

While clock_gettime(CLOCK_MONOTONIC_COARSE) is faster than
clock_gettime(CLOCK_MONOTONIC), the latter is fast enough on Linux for
practical usage, and the difference is negligible compared to other costs
at each event loop iteration.  On the other hand, CLOCK_MONOTONIC_COARSE
causes various issues with typical CONFIG_HZ=250, notably very inaccurate
limit_rate handling in some edge cases (ticket #1678) and negative difference
between $request_time and $upstream_response_time (ticket #1965).

diffstat:

 src/core/ngx_times.c |  4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diffs (14 lines):

diff -r dc955d274130 -r 9e7de0547f09 src/core/ngx_times.c
--- a/src/core/ngx_times.c	Wed Oct 20 09:45:34 2021 +0300
+++ b/src/core/ngx_times.c	Thu Oct 21 18:38:38 2021 +0300
@@ -200,10 +200,6 @@ ngx_monotonic_time(time_t sec, ngx_uint_
 
 #if defined(CLOCK_MONOTONIC_FAST)
     clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
-
-#elif defined(CLOCK_MONOTONIC_COARSE)
-    clock_gettime(CLOCK_MONOTONIC_COARSE, &ts);
-
 #else
     clock_gettime(CLOCK_MONOTONIC, &ts);
 #endif