Date: Sun, 13 Jul 2008 12:09:50 +0200 From: Kris Kennaway <kris@FreeBSD.org> To: Nate Eldredge <neldredge@math.ucsd.edu> Cc: freebsd-hackers@FreeBSD.org Subject: Re: SCHED_4BSD bad interactivity on 7.0 vs 6.3 Message-ID: <4879D46E.7080104@FreeBSD.org> In-Reply-To: <Pine.GSO.4.64.0807130132380.20326@zeno.ucsd.edu> References: <Pine.GSO.4.64.0807121125300.20326@zeno.ucsd.edu> <4879563B.5090201@FreeBSD.org> <Pine.GSO.4.64.0807130132380.20326@zeno.ucsd.edu>
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Nate Eldredge wrote: > 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. > It shows *a* difference, but perhaps not the *same* difference. Please humour me and rule it out. Kris
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