diff options
| author | Eric Dumazet <dada1@cosmosbay.com> | 2009-04-29 14:44:49 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-05-08 15:45:12 -0700 |
| commit | 3209ada8285a9fa6ab8f7a731d54031ec884c745 (patch) | |
| tree | 5c04310aaf84a4799e70b3331ca29d616007e28b | |
| parent | 76e6da3c9e11f2d009a4c519993f29fcd32ae388 (diff) | |
sched: account system time properly
commit f5f293a4e3d0a0c52cec31de6762c95050156516 upstream.
Andrew Gallatin reported that IRQ and SOFTIRQ times were
sometime not reported correctly on recent kernels, and even
bisected to commit 457533a7d3402d1d91fbc125c8bd1bd16dcd3cd4
([PATCH] fix scaled & unscaled cputime accounting) as the first
bad commit.
Further analysis pointed that commit
79741dd35713ff4f6fd0eafd59fa94e8a4ba922d ([PATCH] idle cputime
accounting) was the real cause of the problem.
account_process_tick() was not taking into account timer IRQ
interrupting the idle task servicing a hard or soft irq.
On mostly idle cpu, irqs were thus not accounted and top or
mpstat could tell user/admin that cpu was 100 % idle, 0.00 %
irq, 0.00 % softirq, while it was not.
[ Impact: fix occasionally incorrect CPU statistics in top/mpstat ]
Reported-by: Andrew Gallatin <gallatin@myri.com>
Re-reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: rick.jones2@hp.com
Cc: brice@myri.com
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <49F84BC1.7080602@cosmosbay.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | kernel/sched.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 5e806290fd6..7d13debbaf9 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4347,7 +4347,7 @@ void account_process_tick(struct task_struct *p, int user_tick) if (user_tick) account_user_time(p, one_jiffy, one_jiffy_scaled); - else if (p != rq->idle) + else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) account_system_time(p, HARDIRQ_OFFSET, one_jiffy, one_jiffy_scaled); else |