From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263769AbUGMTpS (ORCPT ); Tue, 13 Jul 2004 15:45:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265737AbUGMTpS (ORCPT ); Tue, 13 Jul 2004 15:45:18 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:49640 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S263769AbUGMTpG (ORCPT ); Tue, 13 Jul 2004 15:45:06 -0400 Subject: Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch From: Lee Revell To: Benno Senoner Cc: "The Linux Audio Developers' Mailing List" , Andrew Morton , arjanv@redhat.com, linux-kernel@vger.kernel.org In-Reply-To: <40F3E31D.9020504@gardena.net> References: <20040709182638.GA11310@elte.hu> <20040710222510.0593f4a4.akpm@osdl.org> <1089673014.10777.42.camel@mindpipe> <20040712163141.31ef1ad6.akpm@osdl.org> <1089677823.10777.64.camel@mindpipe> <40F3E31D.9020504@gardena.net> Content-Type: text/plain Message-Id: <1089747918.22026.6.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Tue, 13 Jul 2004 15:45:18 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2004-07-13 at 09:26, Benno Senoner wrote: > Lee Revell wrote: > > >On Mon, 2004-07-12 at 19:31, Andrew Morton wrote: > > > > > >> > >>OK, thanks. The problem areas there are the timer-based route cache > >>flushing and reiserfs. > >> > >>We can probably fix the route caceh thing by rescheduling the timer after > >>having handled 1000 routes or whatever, although I do wonder if this is a > >>thing we really need to bother about - what else was that machine up to? > >> > >> > >> > > > >Gnutella client. Forgot about that. I agree, it is not reasonable to > >expect low latency with this kind of network traffic happening. I am > >impressed it worked as well as it did. > > > > > > Why not reasonable ? It is very important that networking and HD I/O > both don't interfere with low latency audio. > Think about large audio setups where you use PC hardware to act as > dedicated samplers, software synthesizers etc. Right, I did not think of these. I just meant that you would not typically run Gnutella on a DAW. This should never interfere with audio latency, as Gnutella is running at normal priority and JACK is running SCHED_FIFO. Besides, it looks like there is a real problem with the route cache flushing. I ran the same test with no significant network traffic and I am still seeing spikes in latency. There are all of 5 entries in the route cache. Kernel IP routing cache Source Destination Gateway Flags Metric Ref Use Iface vmail-mx.dca.ne 192.168.2.102 192.168.2.102 l 0 1 838 lo 192.168.2.102 vmail-mx.dca.ne . 0 0 4 eth0 vmail-mx.dca.ne 192.168.2.102 192.168.2.102 l 0 1 838 lo 192.168.2.102 . . 0 0 2 eth0 192.168.2.102 vmail-mx.dca.ne . 0 0 4 eth0 Jul 13 15:15:49 mindpipe kernel: ALSA /usr/src/alsa-cvs-1.0.5/alsa-driver/alsa-kernel/core/pcm_lib.c:169: XRUN: pcmC0D0p Jul 13 15:15:49 mindpipe kernel: [__crc_totalram_pages+1387264/5353478] snd_pcm_period_elapsed+0x2ca/0x410 [snd_pcm] Jul 13 15:15:49 mindpipe kernel: [__crc_totalram_pages+1455070/5353478] snd_emu10k1_interrupt+0x3c8/0x480 [snd_emu10k1] Jul 13 15:15:49 mindpipe kernel: [handle_IRQ_event+49/96] handle_IRQ_event+0x31/0x60 Jul 13 15:15:49 mindpipe kernel: [do_IRQ+155/352] do_IRQ+0x9b/0x160 Jul 13 15:15:49 mindpipe kernel: [common_interrupt+24/32] common_interrupt+0x18/0x20 Jul 13 15:15:49 mindpipe kernel: [rt_run_flush+77/144] rt_run_flush+0x4d/0x90 Jul 13 15:15:49 mindpipe kernel: [rt_secret_rebuild+0/48] rt_secret_rebuild+0x0/0x30 Jul 13 15:15:49 mindpipe kernel: [rt_secret_rebuild+14/48] rt_secret_rebuild+0xe/0x30 Jul 13 15:15:49 mindpipe kernel: [run_timer_softirq+201/416] run_timer_softirq+0xc9/0x1a0 Jul 13 15:15:49 mindpipe kernel: [__do_softirq+131/144] __do_softirq+0x83/0x90 Jul 13 15:15:49 mindpipe kernel: [do_softirq+53/64] do_softirq+0x35/0x40 Jul 13 15:15:49 mindpipe kernel: [do_IRQ+261/352] do_IRQ+0x105/0x160 Jul 13 15:15:49 mindpipe kernel: [common_interrupt+24/32] common_interrupt+0x18/0x20 Jul 13 15:15:49 mindpipe kernel: [default_idle+35/64] default_idle+0x23/0x40 Jul 13 15:15:49 mindpipe kernel: [apm_cpu_idle+165/384] apm_cpu_idle+0xa5/0x180 Jul 13 15:15:49 mindpipe kernel: [cpu_idle+45/64] cpu_idle+0x2d/0x40 Jul 13 15:15:49 mindpipe kernel: [start_kernel+392/464] start_kernel+0x188/0x1d0 Jul 13 15:15:49 mindpipe kernel: Jul 13 15:25:49 mindpipe kernel: ALSA /usr/src/alsa-cvs-1.0.5/alsa-driver/alsa-kernel/core/pcm_lib.c:169: XRUN: pcmC0D0p Jul 13 15:25:49 mindpipe kernel: [__crc_totalram_pages+1387264/5353478] snd_pcm_period_elapsed+0x2ca/0x410 [snd_pcm] Jul 13 15:25:49 mindpipe kernel: [__crc_totalram_pages+1455070/5353478] snd_emu10k1_interrupt+0x3c8/0x480 [snd_emu10k1] Jul 13 15:25:49 mindpipe kernel: [handle_IRQ_event+49/96] handle_IRQ_event+0x31/0x60 Jul 13 15:25:49 mindpipe kernel: [do_IRQ+155/352] do_IRQ+0x9b/0x160 Jul 13 15:25:49 mindpipe kernel: [common_interrupt+24/32] common_interrupt+0x18/0x20 Jul 13 15:25:49 mindpipe kernel: [local_bh_enable+17/112] local_bh_enable+0x11/0x70 Jul 13 15:25:49 mindpipe kernel: [rt_run_flush+92/144] rt_run_flush+0x5c/0x90 Jul 13 15:25:49 mindpipe kernel: [rt_secret_rebuild+0/48] rt_secret_rebuild+0x0/0x30 Jul 13 15:25:49 mindpipe kernel: [rt_secret_rebuild+14/48] rt_secret_rebuild+0xe/0x30 Jul 13 15:25:49 mindpipe kernel: [run_timer_softirq+201/416] run_timer_softirq+0xc9/0x1a0 Jul 13 15:25:49 mindpipe kernel: [__do_softirq+131/144] __do_softirq+0x83/0x90 Jul 13 15:25:49 mindpipe kernel: [do_softirq+53/64] do_softirq+0x35/0x40 Jul 13 15:25:49 mindpipe kernel: [do_IRQ+261/352] do_IRQ+0x105/0x160 Jul 13 15:25:49 mindpipe kernel: [common_interrupt+24/32] common_interrupt+0x18/0x20 Jul 13 15:25:49 mindpipe kernel: [default_idle+35/64] default_idle+0x23/0x40 Jul 13 15:25:49 mindpipe kernel: [apm_cpu_idle+165/384] apm_cpu_idle+0xa5/0x180 Jul 13 15:25:49 mindpipe kernel: [cpu_idle+45/64] cpu_idle+0x2d/0x40 Jul 13 15:25:49 mindpipe kernel: [start_kernel+392/464] start_kernel+0x188/0x1d0 Jul 13 15:25:49 mindpipe kernel: