From: Fred Fan <fanyefeng@gmail.com>
To: cocala <syy.wxd@gmail.com>
Cc: linux-arm-kernel@lists.arm.linux.org.uk, rick.jones2@hp.com,
gallatin@myri.com, akpm@linux-foundation.org,
dada1@cosmosbay.com, schwidefsky@de.ibm.com, brice@myri.com,
paulus@samba.org, benh@kernel.crashing.org, mingo@elte.hu,
gregkh@suse.de, linux-kernel@vger.kernel.org
Subject: Re: inaccurate cpu idle time from top command
Date: Sun, 26 Jul 2009 11:34:02 +0800 [thread overview]
Message-ID: <2f495dc80907252034i4bdd812cx2267d65af7d993d8@mail.gmail.com> (raw)
In-Reply-To: <458a17f90907240745m15c3d7ep893a01a035bf0146@mail.gmail.com>
Hi cocala:
I have met same issue. And we found the total utilization
count(added by idle's utilization) is not 100% in detail processes
information fields.
best Regards
Fred
2009/7/24 cocala <syy.wxd@gmail.com>:
> I saw one commit "3209ada8285a9fa6ab8f7a731d54031ec884c745 - sched: account
> system time properly"
> This commit is to take into account timer IRQ interrupting the idle task
> servicing a hard or soft irq.
>
> If a softirq is started in a tick, all the time in the tick will be counted
> as soft irq time even most time in the tick is idle.
> In our use case, one jiffy is 10ms and the 1G net driver will generate many
> software irq, so the "top" command will show high softare irq time and cpu
> idle time approaches to zero.
> If I change the jiffy to 1ms, the "top" command shows much higher cpu idle
> time. I think this algorithm is also not fair for some cases.
>
> Is there any better way to count the softare irq time?
>
> Thanks
> cocala
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next parent reply other threads:[~2009-07-26 3:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <458a17f90907240745m15c3d7ep893a01a035bf0146@mail.gmail.com>
2009-07-26 3:34 ` Fred Fan [this message]
2009-07-27 7:58 ` Martin Schwidefsky
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