Date: Thu, 17 Aug 2006 09:48:39 -0700 From: Chuck Swiger <cswiger@mac.com> To: Bill LeFebvre <bill@lefebvre.org> Cc: freebsd-stable@freebsd.org Subject: Re: TOP shows above 100% WCPU usage Message-ID: <5C8C1B11-DE0B-4FE2-9A3D-5472650B9FA8@mac.com> In-Reply-To: <44E3FE61.6060800@lefebvre.org> References: <44E1F796.5070105@rogers.com> <20060815172728.GB88051@dan.emsphone.com> <44E204C0.60806@rogers.com> <44E3FE61.6060800@lefebvre.org>
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On Aug 16, 2006, at 10:28 PM, Bill LeFebvre wrote: >>> You have multiple CPUs, so a threaded process can theoretically >>> reach >>> 100*ncpus cpu usage. >>> >> Ahh, thats makes sense, thanks. > > Actually it doesn't. IMO, %CPU should be biased for all available > cpu, not just a single cpu. In other words, a single-threaded > process running on a two processor box should never see more than > 50% cpu. That's how top computes it for SunOS. But for freebsd > top only displays whats in the proc structure and I don't know off- > hand how the kernel records it. You've got a good point here. In particular, consider the case where you have an SMP machine where not all of the CPUs are running at the same clock rate...100% of one CPU is not the same level of processing as 100% of another. -- -Chuck
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