Messages in this thread | | | Date | Fri, 6 Jun 2008 18:05:01 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH -mm 11/25] more aggressively use lumpy reclaim |
| |
On Fri, 06 Jun 2008 16:28:49 -0400 Rik van Riel <riel@redhat.com> wrote:
> From: Rik van Riel <riel@redhat.com> > > During an AIM7 run on a 16GB system, fork started failing around > 32000 threads, despite the system having plenty of free swap and > 15GB of pageable memory.
Can we upadte the changelog to explain why this actually happened?
>From reading the patch I _assume_ that
a) the kernel was using 8k (2-page) stacks and
b) all the memory was stuck on the active list, so reclaim wasn't able to find any order-1 pages and wasn't able to find any order-0 pages which gave it allocatable order-1 pages.
?
> If normal pageout does not result in contiguous free pages for > kernel stacks, fall back to lumpy reclaim instead of failing fork > or doing excessive pageout IO.
hm, I guess that this para kinda says that. Not sure what the "excessive pageout IO" part is referring to?
> I do not know whether this change is needed due to the extreme > stress test or because the inactive list is a smaller fraction > of system memory on huge systems. >
I guess that tweaking the inactive_ratio could be used to determine this?
> > --- > mm/vmscan.c | 20 ++++++++++++++++---- > 1 file changed, 16 insertions(+), 4 deletions(-) > > Index: linux-2.6.26-rc2-mm1/mm/vmscan.c > =================================================================== > --- linux-2.6.26-rc2-mm1.orig/mm/vmscan.c 2008-05-28 12:14:34.000000000 -0400 > +++ linux-2.6.26-rc2-mm1/mm/vmscan.c 2008-05-28 12:14:43.000000000 -0400 > @@ -857,7 +857,8 @@ int isolate_lru_page(struct page *page) > * of reclaimed pages > */ > static unsigned long shrink_inactive_list(unsigned long max_scan, > - struct zone *zone, struct scan_control *sc, int file) > + struct zone *zone, struct scan_control *sc, > + int priority, int file) > { > LIST_HEAD(page_list); > struct pagevec pvec; > @@ -875,8 +876,19 @@ static unsigned long shrink_inactive_lis > unsigned long nr_freed; > unsigned long nr_active; > unsigned int count[NR_LRU_LISTS] = { 0, }; > - int mode = (sc->order > PAGE_ALLOC_COSTLY_ORDER) ? > - ISOLATE_BOTH : ISOLATE_INACTIVE; > + int mode = ISOLATE_INACTIVE; > + > + /* > + * If we need a large contiguous chunk of memory, or have > + * trouble getting a small set of contiguous pages, we > + * will reclaim both active and inactive pages. > + * > + * We use the same threshold as pageout congestion_wait below. > + */ > + if (sc->order > PAGE_ALLOC_COSTLY_ORDER) > + mode = ISOLATE_BOTH; > + else if (sc->order && priority < DEF_PRIORITY - 2) > + mode = ISOLATE_BOTH; > > nr_taken = sc->isolate_pages(sc->swap_cluster_max, > &page_list, &nr_scan, sc->order, mode, > @@ -1171,7 +1183,7 @@ static unsigned long shrink_list(enum lr > shrink_active_list(nr_to_scan, zone, sc, priority, file); > return 0; > } > - return shrink_inactive_list(nr_to_scan, zone, sc, file); > + return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); > }
| |