Date: Sun, 13 Jul 2008 01:34:11 -0700 (PDT) From: Nate Eldredge <neldredge@math.ucsd.edu> To: Kris Kennaway <kris@FreeBSD.org> Cc: freebsd-hackers@FreeBSD.org Subject: Re: SCHED_4BSD bad interactivity on 7.0 vs 6.3 Message-ID: <Pine.GSO.4.64.0807130132380.20326@zeno.ucsd.edu> In-Reply-To: <4879563B.5090201@FreeBSD.org> References: <Pine.GSO.4.64.0807121125300.20326@zeno.ucsd.edu> <4879563B.5090201@FreeBSD.org>
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On Sun, 13 Jul 2008, Kris Kennaway wrote: > Nate Eldredge wrote: >> Hi folks, >> >> Hopefully this is a good list for this topic. >> >> It seems like there has been a regression in interactivity from 6.3-RELEASE >> to 7.0-RELEASE when using the SCHED_4BSD scheduler. After upgrading my >> single-cpu amd64 box, 7.0 has much worse latency. When running a kernel >> compile, there is a noticeable lag to echo my typing or scroll my browser >> windows, and playing an mp3 frequently cuts out for a second or two. This >> did not happen on 6.3-RELEASE. > > Are you sure it's not the x.org server bug that was present in the version > shipped with 7.0? Update to the latest version and see if your X > interactivity improves. Yes, I had not yet upgraded my x.org port when testing this, so it was the same x.org that was fine under 6.3. Also: >> I wrote a small program which forks two processes that run gettimeofday() >> in a tight loop to see how long they get scheduled out. On 6.3 the maximum >> latency is usually under 100 ms. On 7.0 it is 500 ms or more even when >> nothing else is running on the system. When a compile is also running it >> is sometimes 1400 ms or more. This test shows a difference even in single user mode, when X is not running at all. -- Nate Eldredge neldredge@math.ucsd.edu
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