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| author |   Josh Don <joshdon@google.com> | 2021-08-27 09:54:38 -0700 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-10-05 15:51:35 +0200 |
| commit | a130e8fbc7de796eb6e680724d87f4737a26d0ac (patch) | |
| tree | 4adeb41642500b6aca5ddd2b1144a9785e2e591e /kernel/sched/debug.c | |
| parent | sched/core: Simplify core-wide task selection (diff) | |
| download | linux-dev-a130e8fbc7de796eb6e680724d87f4737a26d0ac.tar.xz linux-dev-a130e8fbc7de796eb6e680724d87f4737a26d0ac.zip | |
fs/proc/uptime.c: Fix idle time reporting in /proc/uptime
/proc/uptime reports idle time by reading the CPUTIME_IDLE field from
the per-cpu kcpustats. However, on NO_HZ systems, idle time is not
continually updated on idle cpus, leading this value to appear
incorrectly small.
/proc/stat performs an accounting update when reading idle time; we
can use the same approach for uptime.
With this patch, /proc/stat and /proc/uptime now agree on idle time.
Additionally, the following shows idle time tick up consistently on an
idle machine:
(while true; do cat /proc/uptime; sleep 1; done) | awk '{print $2-prev; prev=$2}'
Reported-by: Luigi Rizzo <lrizzo@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lkml.kernel.org/r/20210827165438.3280779-1-joshdon@google.com
Diffstat (limited to 'kernel/sched/debug.c')
0 files changed, 0 insertions, 0 deletions