From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267511AbUHUKqn (ORCPT ); Sat, 21 Aug 2004 06:46:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267506AbUHUKqn (ORCPT ); Sat, 21 Aug 2004 06:46:43 -0400 Received: from mx2.elte.hu ([157.181.151.9]:54693 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S267511AbUHUKqK (ORCPT ); Sat, 21 Aug 2004 06:46:10 -0400 Date: Sat, 21 Aug 2004 12:46:26 +0200 From: Ingo Molnar To: Lee Revell Cc: linux-kernel , Thomas Charbonnel , Florian Schmidt , Felipe Alfaro Solana , Mark_H_Johnson@raytheon.com Subject: Re: [patch] voluntary-preempt-2.6.8.1-P5 Message-ID: <20040821104626.GA29078@elte.hu> References: <20040817080512.GA1649@elte.hu> <20040819073247.GA1798@elte.hu> <20040820133031.GA13105@elte.hu> <1093058602.854.5.camel@krustophenia.net> <20040821091338.GA25931@elte.hu> <1093079726.854.80.camel@krustophenia.net> <20040821091804.GA26622@elte.hu> <1093080202.854.94.camel@krustophenia.net> <20040821093152.GB27273@elte.hu> <1093081049.854.101.camel@krustophenia.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1093081049.854.101.camel@krustophenia.net> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Lee Revell wrote: > > This one is interesting. What is going on here? > > preemption latency trace v1.0.1 > ------------------------------- > latency: 146 us, entries: 45 (45) > ----------------- > | task: pdflush/33, uid:0 nice:0 policy:0 rt_prio:0 > ----------------- > => started at: find_get_pages_tag+0x19/0x90 > => ended at: find_get_pages_tag+0x61/0x90 > =======> > 00000001 0.000ms (+0.000ms): find_get_pages_tag (pagevec_lookup_tag) > 00000001 0.000ms (+0.000ms): radix_tree_gang_lookup_tag (find_get_pages_tag) > 00000001 0.001ms (+0.000ms): __lookup_tag (radix_tree_gang_lookup_tag) > 00000001 0.007ms (+0.005ms): __lookup_tag (radix_tree_gang_lookup_tag) > > [ 20-30 more of these ] this is the pagevec code, triggering the radix tree multi-entry-lookup code. Could you try to reduce PAGEVEC_SIZE from 16 to 8 (or 4) in include/linux/pagevec.h - does this reduce these particular latencies? Ingo