From owner-freebsd-hackers@FreeBSD.ORG Tue Jul 15 03:31:16 2008 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 996A51065674; Tue, 15 Jul 2008 03:31:16 +0000 (UTC) (envelope-from neldredge@math.ucsd.edu) Received: from euclid.ucsd.edu (euclid.ucsd.edu [132.239.145.52]) by mx1.freebsd.org (Postfix) with ESMTP id 515D98FC16; Tue, 15 Jul 2008 03:31:16 +0000 (UTC) (envelope-from neldredge@math.ucsd.edu) Received: from zeno.ucsd.edu (zeno.ucsd.edu [132.239.145.22]) by euclid.ucsd.edu (8.11.7p3+Sun/8.11.7) with ESMTP id m6F3VFB18667; Mon, 14 Jul 2008 20:31:15 -0700 (PDT) Received: from localhost (neldredg@localhost) by zeno.ucsd.edu (8.11.7p3+Sun/8.11.7) with ESMTP id m6F3VFd23829; Mon, 14 Jul 2008 20:31:15 -0700 (PDT) X-Authentication-Warning: zeno.ucsd.edu: neldredg owned process doing -bs Date: Mon, 14 Jul 2008 20:31:15 -0700 (PDT) From: Nate Eldredge X-X-Sender: neldredg@zeno.ucsd.edu To: Nate Eldredge In-Reply-To: Message-ID: References: <4879563B.5090201@FreeBSD.org> <4879D46E.7080104@FreeBSD.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-hackers@freebsd.org Subject: Re: SCHED_4BSD bad interactivity on 7.0 vs 6.3 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Jul 2008 03:31:16 -0000 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