Date: Fri, 12 Dec 2003 03:05:49 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Andy Farkas <andyf@speednet.com.au> Cc: current@freebsd.org Subject: Re: ULE and current. Message-ID: <20031212025254.F12425@gamplex.bde.org> In-Reply-To: <20031211234620.O15896@hewey.af.speednet.com.au> References: <20031211041048.B4201-100000@mail.chesapeake.net> <20031211234620.O15896@hewey.af.speednet.com.au>
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On Fri, 12 Dec 2003, Andy Farkas wrote: > Bruce Evans wrote: > > [about systat and top] > > Neither; they have different bugs :-). top actually seems to be > > bug-free here, except it intentionally displays percentages that add > > up to a multiple of 100%. This seems to be best. You just have to > > get used to the percentages in the CPU stat line being scaled and the > > others not being scaled. > > So the almost-bug in top(1) is that some CPU percentages are scaled and > some are not scaled? Yes. It's probably more of a documentation bug. > ps. You mentioned "jitter". Thats why I 'sleep 120' in the above tests. > It tends to take about that long for top(1) to settle down. Why is that > so? As all top watchers know, %WCPU and especially %CPU take a while to ramp up with SCHED_4BSD. That's just how the algorithm works. I don't really understand SCHED_ULE, but think it has more jitter in the percentages because it fakes them based on what it is doing based on much less history than SCHED_4BSD (so they are closer to the transient %[W]CPU than the long-term averages). Bruce
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