From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 889028D003B for ; Tue, 19 Apr 2011 07:09:21 -0400 (EDT) Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.221.2]) by mx2.suse.de (Postfix) with ESMTP id A50D786391 for ; Tue, 19 Apr 2011 12:42:39 +0200 (CEST) Date: Tue, 19 Apr 2011 11:47:24 +0200 From: Jan Kara Subject: Re: [PATCH 4/6] writeback: introduce writeback_control.inodes_cleaned Message-ID: <20110419094724.GB5257@quack.suse.cz> References: <20110419030003.108796967@intel.com> <20110419030532.638670778@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110419030532.638670778@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wu Fengguang Cc: Andrew Morton , Jan Kara , Mel Gorman , Mel Gorman , Dave Chinner , Trond Myklebust , Itaru Kitayama , Minchan Kim , LKML , linux-fsdevel@vger.kernel.org, Linux Memory Management List On Tue 19-04-11 11:00:07, Wu Fengguang wrote: > The flusher works on dirty inodes in batches, and may quit prematurely > if the batch of inodes happen to be metadata-only dirtied: in this case > wbc->nr_to_write won't be decreased at all, which stands for "no pages > written" but also mis-interpreted as "no progress". > > So introduce writeback_control.inodes_cleaned to count the inodes get > cleaned. A non-zero value means there are some progress on writeback, > in which case more writeback can be tried. > > about v1: The initial version was to count successful ->write_inode() > calls. However it leads to busy loops for sync() over NFS, because NFS > ridiculously returns 0 (success) while at the same time redirties the > inode. The NFS case can be trivially fixed, however there may be more > hidden bugs in other filesystems.. OK, makes sense. Acked-by: Jan Kara Honza > > Acked-by: Mel Gorman > Signed-off-by: Wu Fengguang > --- > fs/fs-writeback.c | 4 ++++ > include/linux/writeback.h | 1 + > 2 files changed, 5 insertions(+) > > --- linux-next.orig/fs/fs-writeback.c 2011-04-19 10:18:30.000000000 +0800 > +++ linux-next/fs/fs-writeback.c 2011-04-19 10:18:30.000000000 +0800 > @@ -473,6 +473,7 @@ writeback_single_inode(struct inode *ino > * No need to add it back to the LRU. > */ > list_del_init(&inode->i_wb_list); > + wbc->inodes_cleaned++; > } > } > inode_sync_complete(inode); > @@ -736,6 +737,7 @@ static long wb_writeback(struct bdi_writ > wbc.more_io = 0; > wbc.nr_to_write = write_chunk; > wbc.pages_skipped = 0; > + wbc.inodes_cleaned = 0; > > trace_wbc_writeback_start(&wbc, wb->bdi); > if (work->sb) > @@ -752,6 +754,8 @@ static long wb_writeback(struct bdi_writ > */ > if (wbc.nr_to_write <= 0) > continue; > + if (wbc.inodes_cleaned) > + continue; > /* > * Didn't write everything and we don't have more IO, bail > */ > --- linux-next.orig/include/linux/writeback.h 2011-04-19 10:18:17.000000000 +0800 > +++ linux-next/include/linux/writeback.h 2011-04-19 10:18:30.000000000 +0800 > @@ -34,6 +34,7 @@ struct writeback_control { > long nr_to_write; /* Write this many pages, and decrement > this for each page written */ > long pages_skipped; /* Pages which were not written */ > + long inodes_cleaned; /* # of inodes cleaned */ > > /* > * For a_ops->writepages(): is start or end are non-zero then this is > > -- Jan Kara SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org