From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266624AbUGKR36 (ORCPT ); Sun, 11 Jul 2004 13:29:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266626AbUGKR36 (ORCPT ); Sun, 11 Jul 2004 13:29:58 -0400 Received: from rproxy.gmail.com ([64.233.170.202]:3014 "HELO mproxy.gmail.com") by vger.kernel.org with SMTP id S266624AbUGKR3z convert rfc822-to-8bit (ORCPT ); Sun, 11 Jul 2004 13:29:55 -0400 Message-ID: Date: Sun, 11 Jul 2004 14:29:47 -0300 From: =?ISO-8859-1?Q?Andr=E9_Goddard_Rosa?= To: Ingo Molnar Subject: Re: [ck] Re: [announce] [patch] Voluntary Kernel Preemption Patch Cc: Con Kolivas , ck kernel mailing list , Andrew Morton , Arjan van de Ven , linux-kernel@vger.kernel.org In-Reply-To: <20040711143853.GA6555@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT References: <20040709182638.GA11310@elte.hu> <20040709195105.GA4807@infradead.org> <20040710124814.GA27345@elte.hu> <40F0075C.2070607@kolivas.org> <40F016D9.8070300@kolivas.org> <20040711064730.GA11254@elte.hu> <40F14E53.2030300@kolivas.org> <20040711143853.GA6555@elte.hu> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, can anyone explain this: Using Ingo's first patch when I: echo 1 > /proc/sys/kernel/kernel_preempt my system hang up after 2 seconds aproximately. Using Ingo's modifications + Con's it doesn't lock anymore and is the best kernel that I have used to test.. Thanks! On Sun, 11 Jul 2004 16:38:53 +0200, Ingo Molnar wrote: > > > > * Con Kolivas wrote: > > > Ok I've done one better than that ;) I had wli help make some > > instrumentation for me to help find the remaining non preemptible > > kernel portions and set the cutoff to 2ms. Here is what I found: > > > > 7ms non-preemptible critical section violated 2 ms preempt threshold > > starting at reiserfs_sync_fs+0x2d/0xc2 and ending at reiser > > fs_lookup+0xe2/0x221 > > > > 9ms non-preemptible critical section violated 2 ms preempt threshold > > starting at reiserfs_dirty_inode+0x37/0x10e and ending at r > > eiserfs_dirty_inode+0xb0/0x10e > > > > These seem to be the two offenders. Hope this helps. > > great! > > meanwhile i spent an afternoon with another latency testing suite: > > http://www.alsa-project.org/~iwai/latencytest-0.5.3.tar.gz > > it was reporting more accurate latencies, except that there were strange > spikes of latencies. It turned out that for whatever reason, userspace > RDTSC is not always reliable on my box (!). > > I've attached two fixes against latencytest - one makes rdtsc timestamps > more reliable, the other one fixes an SMP bug in the kernel module (it > would lock up under SMP otherwise.). > > here's a latencytest QuickStart: 'cd latencytest; make', then > 'insmod kernel/latency-test.ko', then 'cd tests; ../bin/run_tests'. > > Assuming you have RTC and audio enabled in your kernel it should work > fine. It produces PNGs in the same format as Benno's latencytest suite. > > Ingo > > > -- []s, André