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Open Source and information security mailing list archives
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Date: Mon, 12 Feb 2007 14:32:20 +0000 From: Pavel Machek <pavel@....cz> To: Con Kolivas <kernel@...ivas.org> Cc: Vassili Karpov <av1474@...tv.ru>, linux-kernel@...r.kernel.org Subject: Re: CPU load Hi! > 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. I have (had?) code that 'exploits' this. I believe I could eat 90% of cpu without being noticed. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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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