Date: Thu, 29 Dec 2011 09:47:56 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Alexander Best <arundel@freebsd.org> Subject: Re: starting the annual discussion regarding top(1)'s CPU usage statistics Message-ID: <201112290947.56982.jhb@freebsd.org> In-Reply-To: <20111225214033.GA1933@freebsd.org> References: <20111225214033.GA1933@freebsd.org>
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On Sunday, December 25, 2011 4:40:33 pm Alexander Best wrote: > ok...so we all know that top(1) cannot compute the exact CPU usage for all > processes, since some processes get spawned and exit so fast that they don't > fall into the calculation range. i think nobody is getting angry when top(1) > is off by a few percent. > > however please take a look at the following top(1) output. this is just > ridiculous! out of 800% of CPU power, almost 600% mysteriously vanished. is > there really nothing to improve top(1)'s behaviour when the CPU is dealing with > a lot of short processes (time wise) with a hugh CPU burst? Do you have a lot of short-lived processes? (For example, a -j X build?) top(1) can't do anything about processes it doesn't see (since they are so short-lived and it only samples every N seconds), but those processes still accumulate CPU time and %CPU. -- John Baldwin
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