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Open Source and information security mailing list archives
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Date: Mon, 12 Feb 2007 17:08:14 +1100 From: Con Kolivas <kernel@...ivas.org> To: Stephen Rothwell <sfr@...b.auug.org.au> Cc: "Vassili Karpov" <av1474@...tv.ru>, linux-kernel@...r.kernel.org Subject: Re: CPU load On Monday 12 February 2007 16:55, Stephen Rothwell wrote: > On Mon, 12 Feb 2007 16:44:22 +1100 "Con Kolivas" <kernel@...ivas.org> wrote: > > The kernel looks at what is using cpu _only_ during the timer > > interrupt. Which means if your HZ is 1000 it looks at what is running > > at precisely the moment those 1000 timer ticks occur. It is > > theoretically possible using this measurement system to use >99% cpu > > and record 0 usage if you time your cpu usage properly. It gets even > > more inaccurate at lower HZ values for the same reason. > > That is not true on all architecures, some do more accurate accounting by > recording the times at user/kernel/interrupt transitions ... Indeed. It's certainly the way the common more boring pc architectures do it though. -- -ck - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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