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Date: Mon, 26 Jul 2010 13:59:55 +0100 From: Mel Gorman <mel@....ul.ie> To: Wu Fengguang <fengguang.wu@...el.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>, Chris Mason <chris.mason@...cle.com>, Jens Axboe <jens.axboe@...cle.com>, LKML <linux-kernel@...r.kernel.org>, "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org> Subject: Re: [PATCH 4/6] writeback: sync expired inodes first in background writeback On Mon, Jul 26, 2010 at 08:56:35PM +0800, Wu Fengguang wrote: > > > @@ -232,8 +232,15 @@ static void move_expired_inodes(struct l > > > while (!list_empty(delaying_queue)) { > > > inode = list_entry(delaying_queue->prev, struct inode, i_list); > > > if (expire_interval && > > > - inode_dirtied_after(inode, older_than_this)) > > > - break; > > > + inode_dirtied_after(inode, older_than_this)) { > > > + if (wbc->for_background && > > > + list_empty(dispatch_queue) && list_empty(&tmp)) { > > > + expire_interval >>= 1; > > > + older_than_this = jiffies - expire_interval; > > > + continue; > > > + } else > > > + break; > > > + } > > > > This needs a comment. > > > > I think what it is saying is that if background flush is active but no > > inodes are old enough, consider newer inodes. This is on the assumption > > that page reclaim has encountered dirty pages and the dirty inodes are > > still too young. > > Yes this should be commented. How about this one? > > @@ -232,8 +232,20 @@ static void move_expired_inodes(struct l > while (!list_empty(delaying_queue)) { > inode = list_entry(delaying_queue->prev, struct inode, i_list); > if (expire_interval && > - inode_dirtied_after(inode, older_than_this)) > + inode_dirtied_after(inode, older_than_this)) { > + /* > + * background writeback will start with expired inodes, > + * and then fresh inodes. This order helps reducing > + * the number of dirty pages reaching the end of LRU > + * lists and cause trouble to the page reclaim. > + */ s/reducing/reduce/ Otherwise, it's enough detail to know what is going on. Thanks Thanks > + if (wbc->for_background && > + list_empty(dispatch_queue) && list_empty(&tmp)) { > + expire_interval = 0; > + continue; > + } > break; > + } > if (sb && sb != inode->i_sb) > do_sb_sort = 1; > sb = inode->i_sb; > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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