From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: [PATCH 09/15] writeback: avoid extra sync work at enqueue time Date: Wed, 08 Jun 2011 05:32:45 +0800 Message-ID: <20110607213854.519920424@intel.com> References: <20110607213236.634026193@intel.com> Cc: Jan Kara , Wu Fengguang To: Andrew Morton Return-path: Received: from mga11.intel.com ([192.55.52.93]:11556 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758572Ab1FGVoO (ORCPT ); Tue, 7 Jun 2011 17:44:14 -0400 cc: Dave Chinner cc: Christoph Hellwig cc: Cc: LKML Content-Disposition: inline; filename=writeback-kill-wb_start.patch Sender: linux-fsdevel-owner@vger.kernel.org List-ID: This removes writeback_control.wb_start and does more straightforward sync livelock prevention by setting .older_than_this to prevent extra inodes from being enqueued in the first place. Acked-by: Jan Kara Signed-off-by: Wu Fengguang --- fs/fs-writeback.c | 16 +++------------- include/linux/writeback.h | 3 --- 2 files changed, 3 insertions(+), 16 deletions(-) --- linux-next.orig/fs/fs-writeback.c 2011-05-24 11:17:21.000000000 +0800 +++ linux-next/fs/fs-writeback.c 2011-05-24 11:17:22.000000000 +0800 @@ -544,15 +544,6 @@ static int writeback_sb_inodes(struct su continue; } - /* - * Was this inode dirtied after sync_sb_inodes was called? - * This keeps sync from extra jobs and livelock. - */ - if (inode_dirtied_after(inode, wbc->wb_start)) { - spin_unlock(&inode->i_lock); - return 1; - } - __iget(inode); pages_skipped = wbc->pages_skipped; @@ -585,9 +576,6 @@ static void __writeback_inodes_wb(struct { int ret = 0; - if (!wbc->wb_start) - wbc->wb_start = jiffies; /* livelock avoidance */ - while (!list_empty(&wb->b_io)) { struct inode *inode = wb_inode(wb->b_io.prev); struct super_block *sb = inode->i_sb; @@ -686,7 +674,9 @@ static long wb_writeback(struct bdi_writ if (wbc.sync_mode == WB_SYNC_ALL || wbc.tagged_writepages) write_chunk = LONG_MAX; - wbc.wb_start = jiffies; /* livelock avoidance */ + oldest_jif = jiffies; + wbc.older_than_this = &oldest_jif; + spin_lock(&wb->list_lock); for (;;) { /* --- linux-next.orig/include/linux/writeback.h 2011-05-24 11:17:20.000000000 +0800 +++ linux-next/include/linux/writeback.h 2011-05-24 11:17:22.000000000 +0800 @@ -26,9 +26,6 @@ struct writeback_control { enum writeback_sync_modes sync_mode; unsigned long *older_than_this; /* If !NULL, only write back inodes older than this */ - unsigned long wb_start; /* Time writeback_inodes_wb was - called. This is needed to avoid - extra jobs and livelock */ long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */