Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934153AbZJGINu (ORCPT ); Wed, 7 Oct 2009 04:13:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933264AbZJGIBE (ORCPT ); Wed, 7 Oct 2009 04:01:04 -0400 Received: from mga14.intel.com ([143.182.124.37]:35820 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933086AbZJGIBA (ORCPT ); Wed, 7 Oct 2009 04:01:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,518,1249282800"; d="scan'208";a="195971246" Message-Id: <20091007073818.318088777@intel.com> User-Agent: quilt/0.48-1 Date: Wed, 07 Oct 2009 15:38:18 +0800 From: Wu Fengguang To: Andrew Morton CC: Theodore Tso , Christoph Hellwig , Dave Chinner , Chris Mason , Peter Zijlstra , "Li Shaohua" , "Myklebust Trond" , "jens.axboe@oracle.com" , Jan Kara , Nick Piggin , Cc: Wu Fengguang , LKML Subject: [PATCH 00/45] some writeback experiments Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2913 Lines: 72 Hi all, Here is a collection of writeback patches on - larger writeback chunk sizes - single per-bdi flush thread (killing the foreground throttling writeouts) - lumpy pageout - sync livelock prevention - writeback scheduling - random fixes Sorry for posting a too big series - there are many direct or implicit dependencies, and one patch lead to another before I can stop.. The lumpy pageout and nr_segments support is not complete and do not cover all filesystems for now. It may be better to first convert some of the ->writepages to the generic routines to avoid duplicate work. I managed to address many issues in past week, however there are still known problems. Hints from filesystem developers are highly appreciated. Thanks! The estimated writeback bandwidth is about 1/2 the real throughput for ext2/3/4 and btrfs; noticeable bigger than real throughput for NFS; and cannot be estimated at all for XFS. Very interesting.. NFS writeback is very bumpy. The page numbers and network throughput "freeze" together from time to time: # vmmon -d 1 nr_writeback nr_dirty nr_unstable # (per 1-second samples) nr_writeback nr_dirty nr_unstable 11227 41463 38044 11227 41463 38044 11227 41463 38044 11227 41463 38044 11045 53987 6490 11033 53120 8145 11195 52143 10886 11211 52144 10913 11211 52144 10913 11211 52144 10913 btrfs seems to maintain a private pool of writeback pages, which can go out of control: nr_writeback nr_dirty 261075 132 252891 195 244795 187 236851 187 228830 187 221040 218 212674 237 204981 237 XFS has very interesting "bumpy writeback" behavior: it tends to wait collect enough pages and then write the whole world. nr_writeback nr_dirty 80781 0 37117 37703 37117 43933 81044 6 81050 0 43943 10199 43930 36355 43930 36355 80293 0 80285 0 80285 0 Thanks, Fengguang -- 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/