On Sat, 31 Dec 2011 23:18:15 -0800 (PST) Hugh Dickins <hughd@xxxxxxxxxx> wrote: > On Thu, 29 Dec 2011, Andrew Morton wrote: > > > > This is not all some handwavy theoretical thing either. If we've gone > > and introduced serious latency issues, people *will* hit them and treat > > it as a regression. > > Sure, though the worst I've seen so far (probably haven't been trying > hard enough yet, I need to go for THPs) is 39 pages freed in one call. 39 is OK. How hugepage-intensive was the workload? > Regression? Well, any bad latency would already have been there on > the gathering side. > > > > > Now, a way out here is to remove lumpy reclaim (please). And make the > > problem not come back by promising to never call putback_lru_pages(lots > > of pages) (how do we do this?). > > We can very easily put a counter in it, doing a spin_unlock_irq every > time we hit the max. Nothing prevents that, it's just an excrescence > I'd have preferred to omit and have not today implemented. Yes. It's ultra-cautious, but perhaps we should do this at least until lumpy goes away. > > > > So I think the best way ahead here is to distribute this patch in the > > same release in which we remove lumpy reclaim (pokes Mel). > > I'm sure there are better reasons for removing lumpy than that I posted > a patch which happened to remove some limitation. No need to poke Mel > on my behalf! No harm done - Mel's been getting rather unpoked lately. Not that poking works very well anyway <checks to see if mm/thrash.c is still there> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>