From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267895AbUHPTUE (ORCPT ); Mon, 16 Aug 2004 15:20:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267896AbUHPTUE (ORCPT ); Mon, 16 Aug 2004 15:20:04 -0400 Received: from rwcrmhc11.comcast.net ([204.127.198.35]:14764 "EHLO rwcrmhc11.comcast.net") by vger.kernel.org with ESMTP id S267895AbUHPTT6 (ORCPT ); Mon, 16 Aug 2004 15:19:58 -0400 Message-ID: <412108E0.4090300@namesys.com> Date: Mon, 16 Aug 2004 12:20:00 -0700 From: Hans Reiser User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040113 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ingo Molnar CC: Thomas Charbonnel , Lee Revell , Florian Schmidt , linux-kernel , Felipe Alfaro Solana Subject: Re: [patch] voluntary-preempt-2.6.8.1-P1 References: <1092622121.867.109.camel@krustophenia.net> <20040816023655.GA8746@elte.hu> <1092624221.867.118.camel@krustophenia.net> <20040816032806.GA11750@elte.hu> <20040816033623.GA12157@elte.hu> <1092627691.867.150.camel@krustophenia.net> <20040816034618.GA13063@elte.hu> <1092628493.810.3.camel@krustophenia.net> <20040816040515.GA13665@elte.hu> <1092654819.5057.18.camel@localhost> <20040816113131.GA30527@elte.hu> In-Reply-To: <20040816113131.GA30527@elte.hu> X-Enigmail-Version: 0.83.3.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: >* Thomas Charbonnel wrote: > > > >>Tested P1. The biggest offender on my system is still reiserfs' >>search_by_key. The trace is made of a very long loop of : >> 0.016ms (+0.000ms): reiserfs_in_journal (scan_bitmap_block) >> 0.016ms (+0.000ms): find_next_zero_bit (scan_bitmap_block) >>(...) >> 0.977ms (+0.000ms): reiserfs_in_journal (scan_bitmap_block) >> 0.977ms (+0.000ms): find_next_zero_bit (scan_bitmap_block) >>with interrupts showing up in the trace from time to time. Do you have >>plans to fix this, or should I switch to ext3 ? >> >> > >i took a quick look and the reiserfs locking rules in that place do not >seem to be easily fixable - this is the tree-lookup code which i suspect >cannot be preempted. The reiser journalling code also makes use of the >big kernel lock. I'd suggest reporting this to the reiserfs folks > the fix to reiserfs doing single threaded balancing/searching is called reiser4;-) It was not a trivial fix. It is however released. > and >(if it's not too much effort to migrate) use ext3 meanwhile. > > > >>but the weird thing is that the latency sum goes way above those 100us, >>the culprit being do_IRQ, regularly chewing up to 1ms ! >> >> > > > >> 0.011ms (+0.000ms): enable_8259A_irq (startup_8259A_irq) >> 0.954ms (+0.943ms): do_IRQ (common_interrupt) >> >> > >weird. This has the looks of a preempt-timing bug (we get a timer IRQ >every 1 msec) - but there should be no preempt-timing when we are in the >idle task (swapper). > > > >>http://www.undata.org/~thomas/swapper.trace >> >> > >i'll upload -P2 in a couple of minutes, it will trace the code that >do_IRQ() interrupted too - that would be quite useful in your case. > > Ingo >- >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html >Please read the FAQ at http://www.tux.org/lkml/ > > > >