From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28 Date: Mon, 17 Nov 2008 01:14:03 -0800 (PST) Message-ID: <20081117.011403.06989342.davem@davemloft.net> References: <1ScKicKnTUE.A.VxH.DIHIJB@chimera> <20081117090648.GG28786@elte.hu> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081117090648.GG28786-X9Un+BFzKDI@public.gmane.org> Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="us-ascii" To: mingo-X9Un+BFzKDI@public.gmane.org Cc: rjw-KKrjLPT3xs0@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-testers-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cl-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, efault-Mmb7MZpHnFY@public.gmane.org, a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org From: Ingo Molnar Date: Mon, 17 Nov 2008 10:06:48 +0100 > > * Rafael J. Wysocki wrote: > > > This message has been generated automatically as a part of a report > > of regressions introduced between 2.6.26 and 2.6.27. > > > > The following bug entry is on the current list of known regressions > > introduced between 2.6.26 and 2.6.27. Please verify if it still should > > be listed and let me know (either way). > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=11308 > > Subject : tbench regression on each kernel release from 2.6.22 -> 2.6.28 > > Submitter : Christoph Lameter > > Date : 2008-08-11 18:36 (98 days old) > > References : http://marc.info/?l=linux-kernel&m=121847986119495&w=4 > > http://marc.info/?l=linux-kernel&m=122125737421332&w=4 > > Christoph, as per the recent analysis of Mike: > > http://fixunix.com/kernel/556867-regression-benchmark-throughput-loss-a622cf6-f7160c7-pull.html > > all scheduler components of this regression have been eliminated. > > In fact his numbers show that scheduler speedups since 2.6.22 have > offset and hidden most other sources of tbench regression. (i.e. the > scheduler portion got 5% faster, hence it was able to offset a > slowdown of 5% in other areas of the kernel that tbench triggers) Although I respect the improvements, wake_up() is still several orders of magnitude slower than it was in 2.6.22 and wake_up() is at the top of the profiles in tbench runs. It really is premature to close this regression at this time. I am working with every spare moment I have to try and nail this stuff, but unless someone else helps me people need to be patient.