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Commit f5f293a4 authored by Eric Dumazet's avatar Eric Dumazet Committed by Ingo Molnar
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sched: account system time properly



Andrew Gallatin reported that IRQ and SOFTIRQ times were
sometime not reported correctly on recent kernels, and even
bisected to commit 457533a7
([PATCH] fix scaled & unscaled cputime accounting) as the first
bad commit.

Further analysis pointed that commit
79741dd3 ([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: default avatarAndrew Gallatin <gallatin@myri.com>
Re-reported-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Acked-by: default avatarMartin 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: default avatarIngo Molnar <mingo@elte.hu>
parent 56a50add
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