From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264585AbUGWXuV (ORCPT ); Fri, 23 Jul 2004 19:50:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268184AbUGWXuV (ORCPT ); Fri, 23 Jul 2004 19:50:21 -0400 Received: from pD9517AB1.dip.t-dialin.net ([217.81.122.177]:20097 "EHLO undata.org") by vger.kernel.org with ESMTP id S264585AbUGWXuI (ORCPT ); Fri, 23 Jul 2004 19:50:08 -0400 Subject: Re: [patch] voluntary-preempt-2.6.8-rc2-I3 From: Thomas Charbonnel To: Ingo Molnar Cc: linux-kernel@vger.kernel.org In-Reply-To: <20040723120014.GA5573@elte.hu> References: <20040722161941.GA23972@elte.hu> <20040722172428.GA5632@ss1000.ms.mff.cuni.cz> <20040722175457.GA5855@ss1000.ms.mff.cuni.cz> <20040722180142.GC30059@elte.hu> <20040722180821.GA377@elte.hu> <20040722181426.GA892@elte.hu> <20040723104246.GA2752@elte.hu> <4d8e3fd30407230358141e0e58@mail.gmail.com> <20040723110430.GA3787@elte.hu> <4d8e3fd30407230442afe80c1@mail.gmail.com> <20040723120014.GA5573@elte.hu> Content-Type: text/plain Message-Id: <1090626523.4851.32.camel@localhost> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Sat, 24 Jul 2004 01:48:43 +0200 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > All known performance problems have been fixed in -I4. The focus is > mainly on latency. You can best support this patch by trying it out and > doing measurements - both latency and throughput measurements are > welcome. Latency measurement can be done via the latencytest tool: > > http://www.alsa-project.org/~iwai/latencytest-0.5.4.tar.gz > > If you enable both CONFIG_PREEMPT_VOLUNTARY and CONFIG_PREEMPT then you > can use the /proc/sys/kernel/voluntary_preemption|kernel_preemption > sysctl knobs to turn the preemption features on/off. The following flag > combinations can be used to do comparisons: > > vanilla: vp:0 kp:0 > CONFIG_PREEMPT: vp:0 kp:1 > voluntary-preempt: vp:1 kp:0 > voluntary-preempt + CONFIG_PREEMPT: vp:1 kp:1 > voluntary-preempt + softirq defer: vp:2 kp:0 [default] > voluntary-preempt + softirq defer + CONFIG_PREEMPT: vp:2 kp:1 > > each of the above combinations should work and should pretty exactly > represent that particular kernel (i.e. you can get vanilla > non-preemptible 2.6.8-rc2 kernel behavior by switching both flags on) - > but i typically use the default one for testing. > > Ingo Hi, I'm experiencing hard freezes in the early stage of the latency test suite (X11 test, latencytest-0.5.4) with 2.6.8-rc2-I4, both with the default vp:2 kp:0 and with vp:0 kp:0 (nvidia card, xfree drivers). I was also experiencing hard freezes before with 2.6.7-mm7-H4 while doing intensive disk I/O on reiserfs (e.g. tar big_file.tar.gz) As for the tests, I have 2 remaining problems, one with mmap in conjunction with mlockall(MCL_CURRENT|MCL_FUTURE) : XRUN: pcmC2D0c [] dump_stack+0x1e/0x30 [] snd_pcm_period_elapsed+0x2e1/0x420 [] snd_hdsp_interrupt+0x174/0x180 [] handle_IRQ_event+0x3b/0x70 [] do_IRQ+0x96/0x150 [] common_interrupt+0x18/0x20 [] do_no_page+0x5f/0x300 [] handle_mm_fault+0xe2/0x190 [] get_user_pages+0x130/0x370 [] make_pages_present+0x87/0xb0 [] do_mmap_pgoff+0x476/0x6d0 [] sys_mmap2+0xa0/0xe0 [] sysenter_past_esp+0x52/0x71 XRUN: pcmC2D0p [] dump_stack+0x1e/0x30 [] snd_pcm_period_elapsed+0x2e1/0x420 [] snd_hdsp_interrupt+0x154/0x180 [] handle_IRQ_event+0x3b/0x70 [] do_IRQ+0x96/0x150 [] common_interrupt+0x18/0x20 [] do_no_page+0x5f/0x300 [] handle_mm_fault+0xe2/0x190 [] get_user_pages+0x130/0x370 [] make_pages_present+0x87/0xb0 [] do_mmap_pgoff+0x476/0x6d0 [] sys_mmap2+0xa0/0xe0 [] sysenter_past_esp+0x52/0x71 and the other one when accessing the keyboard at a sensible moment. Such a moment occurs rather precisely every 8.079 seconds on my system (+/- 2ms). I could verify this by keeping a key pressed (xrun every 8.079 second), or just using the keyboard normally (xruns happen more or less randomly but the time interval to the previous one is always a multiple of this 8.079 period) : XRUN: pcmC2D0c [] dump_stack+0x1e/0x30 [] snd_pcm_period_elapsed+0x2e1/0x420 [] snd_hdsp_interrupt+0x174/0x180 [] handle_IRQ_event+0x3b/0x70 [] do_IRQ+0x96/0x150 [] common_interrupt+0x18/0x20 [] do_IRQ+0x96/0x150 [] common_interrupt+0x18/0x20 [] cpu_idle+0x34/0x40 [] start_kernel+0x16d/0x190 [] 0xc010019f Can you think of a possible explanation for this one ? Thomas