lkml.org 
[lkml]   [2016]   [Aug]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[patch] sched/cputime: Fix NO_HZ_FULL getrusage() monotonicity regression
From
Date
Hi Peter,

While running ltp, the fates decided it was time for me to encounter
the roughly 1 out of every 10 call failure below. As much as I run
ltp, I'm a bit surprised that I (or anyone else) haven't met this
before, but then the fates are known to be a tad fickle.

getrusage04 0 TINFO : Expected timers granularity is 4000 us
getrusage04 0 TINFO : Using 1 as multiply factor for max [us]time increment (1000+4000us)!
getrusage04 0 TINFO : utime: 0us; stime: 179us
getrusage04 0 TINFO : utime: 3751us; stime: 0us
getrusage04 1 TFAIL : getrusage04.c:133: stime increased > 5000us:

When applying the full rtime to either stime or utime, do not overwrite
the previously tallied value.

Fixes: 9d7fb0427648 ("sched/cputime: Guarantee stime + utime == rtime")
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: stable@vger.kernel.org # 4.3+
---
kernel/sched/cputime.c | 2 ++
1 file changed, 2 insertions(+)

--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -608,11 +608,13 @@ static void cputime_adjust(struct task_c

if (utime == 0) {
stime = rtime;
+ utime = prev->utime;
goto update;
}

if (stime == 0) {
utime = rtime;
+ stime = prev->stime;
goto update;
}

\
 
 \ /
  Last update: 2016-08-10 22:41    [W:0.123 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site