On Mon, Jul 26, 2010 at 08:20:54PM +0800, Jan Kara wrote: > On Mon 26-07-10 20:00:11, Wu Fengguang wrote: > > On Mon, Jul 26, 2010 at 06:57:37PM +0800, Mel Gorman wrote: > > > On Thu, Jul 22, 2010 at 01:09:32PM +0800, Wu Fengguang wrote: > > > > A background flush work may run for ever. So it's reasonable for it to > > > > mimic the kupdate behavior of syncing old/expired inodes first. > > > > > > > > The policy is > > > > - enqueue all newly expired inodes at each queue_io() time > > > > - retry with halfed expire interval until get some inodes to sync > > > > > > > > CC: Jan Kara <jack@xxxxxxx> > > > > Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> > > > > > > Ok, intuitively this would appear to tie into pageout where we want > > > older inodes to be cleaned first by background flushers to limit the > > > number of dirty pages encountered by page reclaim. If this is accurate, > > > it should be detailed in the changelog. > > > > Good suggestion. I'll add these lines: > > > > This is to help reduce the number of dirty pages encountered by page > > reclaim, eg. the pageout() calls. Normally older inodes contain older > > dirty pages, which are more close to the end of the LRU lists. So > Well, this kind of implicitely assumes that once page is written, it > doesn't get accessed anymore, right? No, this patch is not evicting the page :) > Which I imagine is often true but > not for all workloads... Anyway I think this behavior is a good start > also because it is kind of natural to users to see "old" files written > first. Thanks, Fengguang > > syncing older inodes first helps reducing the dirty pages reached by > > the page reclaim code. > > Honza > -- > Jan Kara <jack@xxxxxxx> > SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>