On Mon, Jul 26, 2010 at 12:11:59PM +0800, Minchan Kim wrote: > On Mon, Jul 26, 2010 at 12:27 PM, Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote: > > On Sun, Jul 25, 2010 at 08:03:45PM +0800, Minchan Kim wrote: > >> On Sun, Jul 25, 2010 at 07:43:20PM +0900, KOSAKI Motohiro wrote: > >> > Hi > >> > > >> > sorry for the delay. > >> > > >> > > Will you be picking it up or should I? The changelog should be more or less > >> > > the same as yours and consider it > >> > > > >> > > Signed-off-by: Mel Gorman <mel@xxxxxxxxx> > >> > > > >> > > It'd be nice if the original tester is still knocking around and willing > >> > > to confirm the patch resolves his/her problem. I am running this patch on > >> > > my desktop at the moment and it does feel a little smoother but it might be > >> > > my imagination. I had trouble with odd stalls that I never pinned down and > >> > > was attributing to the machine being commonly heavily loaded but I haven't > >> > > noticed them today. > >> > > > >> > > It also needs an Acked-by or Reviewed-by from Kosaki Motohiro as it alters > >> > > logic he introduced in commit [78dc583: vmscan: low order lumpy reclaim also > >> > > should use PAGEOUT_IO_SYNC] > >> > > >> > My reviewing doesn't found any bug. however I think original thread have too many guess > >> > and we need to know reproduce way and confirm it. > >> > > >> > At least, we need three confirms. > >> > o original issue is still there? > >> > o DEF_PRIORITY/3 is best value? > >> > >> I agree. Wu, how do you determine DEF_PRIORITY/3 of LRU? > >> I guess system has 512M and 22M writeback pages. > >> So you may determine it for skipping max 32M writeback pages. > >> Is right? > > > > For 512M mem, DEF_PRIORITY/3 means 32M dirty _or_ writeback pages. > > Because shrink_inactive_list() first calls > > shrink_page_list(PAGEOUT_IO_ASYNC) then optionally > > shrink_page_list(PAGEOUT_IO_SYNC), so dirty pages will first be > > converted to writeback pages and then optionally be waited on. > > > > The dirty/writeback pages may go up to 512M*20% = 100M. So 32M looks > > a reasonable value. > > Why do you think it's a reasonable value? > I mean why isn't it good 12.5% or 3.125%? Why do you select 6.25%? > I am not against you. Just out of curiosity and requires more explanation. > It might be thing _only I_ don't know. :( It's more or less random selected. I'm also OK with 3.125%. It's an threshold to turn on some _last resort_ mechanism, so don't need to be optimal.. > > > >> And I have a question of your below comment. > >> > >> "As the default dirty throttle ratio is 20%, sync write&wait > >> will hardly be triggered by pure dirty pages" > >> > >> I am not sure exactly what you mean but at least DEF_PRIOIRTY/3 seems to be > >> related to dirty_ratio. It always can be changed by admin. > >> Then do we have to determine magic value(DEF_PRIORITY/3) proportional to dirty_ratio? > > > > Yes DEF_PRIORITY/3 is already proportional to the _default_ > > dirty_ratio. We could do explicit comparison with dirty_ratio > > just in case dirty_ratio get changed by user. It's mainly a question > > of whether deserving to add such overheads and complexity. I'd prefer > > to keep the current simple form :) > > What I suggest is that couldn't we use recent_writeback/recent_scanned ratio? > I think scan_control's new filed and counting wouldn't be a big > overhead and complexity. > I am not sure which ratio is best. but at least, it would make the > logic scalable and sense to me. :) ..and don't need to be elaborated :) Thanks, Fengguang -- 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>