From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: [PATCH] Prevent large file writeback starvation Date: Mon, 06 Feb 2006 09:36:04 -0500 Message-ID: <43E75ED4.809@rtr.ca> References: <20060206040027.GI43335175@melbourne.sgi.com> <20060205202733.48a02dbe.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Chinner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Return-path: Received: from rtr.ca ([64.26.128.89]:43148 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S1751095AbWBFOgL (ORCPT ); Mon, 6 Feb 2006 09:36:11 -0500 To: Andrew Morton In-Reply-To: <20060205202733.48a02dbe.akpm@osdl.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org I wonder if this is related to my previous observation here, on ext3, that large file writebacks get deferred wayyyyy too long. Original post is below: -------- Original Message -------- Subject: 2.6.xx: dirty pages never being sync'd to disk? Date: Mon, 14 Nov 2005 10:30:58 -0500 From: Mark Lord To: Linux Kernel Okay, this one's been nagging me since I first began using 2.6.xx. My Notebook computer has 2GB of RAM, and the 2.6.xx kernel seems quite happy to leave hundreds of MB of dirty unsync'd pages laying around more or less indefinitely. This worries me, because that's a lot of data to lose should the kernel crash (which it has once quite recently) or the battery die. /proc/sys/vm/dirty_expire_centisecs = 3000 (30 seconds) /proc/sys/vm/dirty_writeback_centisecs = 500 (5 seconds) My understanding (please correct if wrong) is that this means that any (file data) page which is dirtied, should get flushed back to disk after 30 seconds or so. That doesn't happen here. Hundreds of MB of dirty pages just hang around indefinitely, until I manually type "sync", at which point the hard drive gets very busy for 20 seconds or so. What's going on?