From: Nick Bowler Subject: ext3: massive latencies for some write operations Date: Thu, 25 Jun 2009 22:18:16 -0400 Message-ID: <97c719fa0906251918i5b047943yde752774c686f301@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: calvin.walton@gmail.com To: linux-ext4@vger.kernel.org Return-path: Received: from mail-qy0-f193.google.com ([209.85.221.193]:55690 "EHLO mail-qy0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752443AbZFZCSO (ORCPT ); Thu, 25 Jun 2009 22:18:14 -0400 Received: by qyk31 with SMTP id 31so2600202qyk.33 for ; Thu, 25 Jun 2009 19:18:16 -0700 (PDT) Sender: linux-ext4-owner@vger.kernel.org List-ID: I wasn't entirely sure which list to post this on, this one seemed to fit best. Apologies if there was a better place. Please CC any replies to me me as I am not subscribed to the list. Recently, I've been experiencing enormous (more than a minute) latencies during some write operations to my /home filesystem. During such a time, many programs tend to completely stop responding, although programs doing continuous reads (e.g. music or video players) appear to be unaffected. The filesystem is a 3TB ext3 filesystem on a software raid-5 array (4x 1TB drives). Dmesg is completely silent. I'm on an amd64 running 2.6.30. However, I had these issues on 2.6.26 and 2.6.29 as well. Latencytop output follows. LatencyTOP version 0.4 (C) 2008 Intel Corporation Cause Maximum Percentage start_this_handle journal_start ext3_journal_start68746.9 msec 44.3 % start_this_handle journal_start ext3_journal_start59219.1 msec 38.1 % sync_page sync_page_killable __lock_page_killable 448.1 msec 2.3 % sync_buffer __wait_on_buffer ext4_bread ext4_find_445.0 msec 1.6 % sync_page __lock_page find_lock_page filemap_fault 84.5 msec 0.4 % do_get_write_access journal_get_write_access __ext 78.2 msec 0.1 % do_get_write_access journal_get_write_access __ext 70.0 msec 0.0 % md_write_start make_request md_make_request generi 66.9 msec 0.6 % sync_buffer __wait_on_buffer ext4_bread ext4_find_ 61.1 msec 0.2 % Process amuled (19428) Total: 69182.1 msec start_this_handle journal_start ext3_journal_start68746.9 msec 99.4 %do_ sync_page __lock_page find_lock_page filemap_fault 84.5 msec 0.3 %lt do sync_page sync_page_killable __lock_page_killable 20.9 msec 0.0 %sync_ sync_buffer __wait_on_buffer __ext3_get_inode_loc 15.8 msec 0.0 %looku sync_buffer __wait_on_buffer __bread ext3_get_bran 11.4 msec 0.0 % ext3 hrtimer_nanosleep sys_nanosleep system_call_fastpa 4.9 msec 0.1 %_read