Date: Mon, 14 Jul 2008 20:31:15 -0700 (PDT) From: Nate Eldredge <neldredge@math.ucsd.edu> 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: <Pine.GSO.4.64.0807142030070.20326@zeno.ucsd.edu> In-Reply-To: <Pine.GSO.4.64.0807131237150.20326@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> <4879D46E.7080104@FreeBSD.org> <Pine.GSO.4.64.0807131237150.20326@zeno.ucsd.edu>
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On Sun, 13 Jul 2008, Nate Eldredge wrote: > 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. After trying this, I can't seem to reproduce the sound skipping behavior, unless I do something fairly extreme like "make -j 6". But the mouse does seem to skip when a compile is running, so I do believe there is a regression. -- Nate Eldredge neldredge@math.ucsd.edu
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