Date: Mon, 11 Jul 2011 18:14:12 +0200 From: Ivan Voras <ivoras@freebsd.org> To: Andriy Gapon <avg@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: Heavy I/O blocks FreeBSD box for several seconds Message-ID: <CAF-QHFUk2Ab32HLJnRXFoBG53Z26fEq-qTv1r24iFuB9wwahwg@mail.gmail.com> In-Reply-To: <4E1B1198.6090308@FreeBSD.org> References: <20110706170132.GA68775@troutmask.apl.washington.edu> <5080.1309971941@critter.freebsd.dk> <20110706180001.GA69157@troutmask.apl.washington.edu> <4E14A54A.4050106@freebsd.org> <4E155FF9.5090905@FreeBSD.org> <20110707151440.GA75537@troutmask.apl.washington.edu> <4E160C2F.8020001@FreeBSD.org> <20110707200845.GA77049@troutmask.apl.washington.edu> <ivf221$oo2$1@dough.gmane.org> <4E1B1198.6090308@FreeBSD.org>
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On 11 July 2011 17:07, Andriy Gapon <avg@freebsd.org> wrote: > Yeah, but what problem is demonstrated here? > Are we confident that non-even workload is inherently bad? > E.g.: > 79.39 + .. + 77.59 < 5 * 80 =3D 400 > 100.00 + ... + 55.18 ~~ 402 which is more than theoretically possible :-) > So it would _appear_ that with ULE we get more work out of available CPUs= . It depends... I am not really concerned about the percentages; for many things, including "green computing" and TurboBoost it is beneficial to have one loaded CPU core and the rest of them idling (so they can be slowed down, or the loaded ones "boosted" - if we even support this). >> PID USERNAME THR PRI NICE SIZE RES STATE C TIME CPU COMM= AND >> 1318 kargl 1 103 0 370M 294M CPU0 0 1:31 100.00% sas= mp >> 1319 kargl 1 103 0 370M 294M RUN 1 1:29 100.00% sas= mp >> 1322 kargl 1 99 0 370M 294M CPU2 2 1:03 87.26% sasm= p >> 1320 kargl 1 91 0 370M 294M RUN 3 1:07 60.79% sasm= p >> 1321 kargl 1 89 0 370M 294M CPU3 3 1:06 55.18% sasm= p What I'd like to know is how do the priority calculations come into this - as the OP's problem sort of reminds of livelocking. > P.S. Not saying that this is the case here, but I've seen the following s= cenario > in real life. =C2=A0People add only nominal support for some platform in = their software > - when they don't know how to properly implement some feature, they just = drop that > feature or implement it very suboptimally. =C2=A0Then other people use ba= d performance > of that software on that platform as indication that there is something w= rong with > the platform, not the software. Yes but as a minority platform, it eventually becomes "our" problem...
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