Date: Mon, 21 Nov 2011 11:37:21 -0500 From: Ryan Stone <rysto32@gmail.com> To: Eugene Grosbein <eugen@grosbein.pp.ru> Cc: hackers@freebsd.org Subject: Re: dummynet(4) kernel process CPU usage monitoring Message-ID: <CAFMmRNzKRxqj3dp_8fHzniQ%2BRtTiSN0wxPjcMa9pP97n1=Bxtg@mail.gmail.com> In-Reply-To: <4EC9EE5A.2070204@grosbein.pp.ru> References: <4EC39367.4030109@rdtc.ru> <4EC9EE5A.2070204@grosbein.pp.ru>
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On Mon, Nov 21, 2011 at 1:23 AM, Eugene Grosbein <eugen@grosbein.pp.ru> wrote: > Hi! > > I need to draw graph of dummynet's CPU usage. > "procstat -t 0" shows me TID (thread id) of dummynet kernel thread. > "ps -Hxo time,lwp" shows me total CPU time consumed by this thread. > > Now I see this time has 9 seconds increase during 60 seconds of real time. > This should be 9/60=15% CPU usage, but "top -SHP" shows me 0.00% meantime. > > Where is my error? > > Eugene Grosbein Which version are you running? 8.1-RELEASE and older have the problem that the scheduler and the CPU statistics gatherer are driven from the same clock. For threads that tend to frequently wake up and run for less than a full tick(dummynet would appear to fall in this category) this means that CPU usage statistics are never captured at a point where those threads are running, so top shows 0% for those threads. I am told that some relatively recent timer-related work(eventtimer?) should have resolved the issue, which is definitely in 9.0 and might be in stable/8 and may even have made it into 8.2-RELEASE.
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