Date: Sun, 13 Jul 2008 12:38:24 -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.4.64.0807131237150.20326@zeno.ucsd.edu> In-Reply-To: <4879D46E.7080104@FreeBSD.org> References: <Pine.GSO.4.64.0807121125300.20326@zeno.ucsd.edu> <4879563B.5090201@FreeBSD.org> <Pine.GSO.4.64.0807130132380.20326@zeno.ucsd.edu> <4879D46E.7080104@FreeBSD.org>
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On Sun, 13 Jul 2008, Kris Kennaway wrote: > 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. Okay. I am in the process of recompiling all my ports, so after that is done I will boot with a GENERIC kernel and see what happens. -- Nate Eldredge neldredge@math.ucsd.edu
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