Hi,
[Same patch as earlier sent to linux-mm, now tested]
Patch is agains 2.4.8-pre3, but should apply cleanly.
The only performance difference I have noticed is for copying
a huge file, then it performs a lot better (but I do not have a
baseline run for an unpatched -pre3, but I have benchmarked
both earlier and later revisions)
* The original code in __alloc_pages_limit has a little bug in
the case when:
- kreclaimd were not allowed to run for a LONG time...
Lots of kernel activity, RT tasks, or code running
around for a long time allocating memory.
- there were lots of inactive clean pages
- pages were allocated without direct_reclaim (higher order)
(networking might be one candidate)
it could result in using up ALL free pages!
This patch tries to prevent this situation in several ways:
1) Do not allow to alloc a free page when they are critically low.
[last line of patch, the really critical part of this patch]
2) If direct reclaims are allowed do some additional work.
reclaim & free until pages_min,
alloc one page,
reclaim and free until pages_low
/RogerL
-- Roger Larsson Skellefteċ Sweden******************************************* Patch prepared by: roger.larsson@norran.net with comments from Riel
--- linux/mm/page_alloc.c.orig Wed Aug 22 13:36:57 2001 +++ linux/mm/page_alloc.c Thu Aug 23 01:15:17 2001 @@ -253,11 +253,35 @@
if (z->free_pages + z->inactive_clean_pages >= water_mark) { struct page *page = NULL; - /* If possible, reclaim a page directly. */ - if (direct_reclaim) + + /* + * Reclaim a page from the inactive_clean list. + * If needed, refill the free list up to the + * low water mark. + */ + if (direct_reclaim) { page = reclaim_page(z); - /* If that fails, fall back to rmqueue. */ - if (!page) + + while (page && z->free_pages < z->pages_min) { + __free_page(page); + page = reclaim_page(z); + } + + if (page) { + while (z->free_pages < z->pages_low) { + struct page *extra = reclaim_page(z); + if (!extra) + break; + __free_page(extra); + } + } + + /* let kreclaimd handle up to pages_high */ + } + /* If that fails, fall back to rmqueue, but never let + * free_pages go below pages_min... + */ + if (!page && z->free_pages >= z->pages_min) page = rmqueue(z, order); if (page) return page; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Aug 23 2001 - 21:01:00 EST