The patch titled page allocator: move check for disabled anti-fragmentation out of fastpath has been added to the -mm tree. Its filename is page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: page allocator: move check for disabled anti-fragmentation out of fastpath From: Mel Gorman <mel@xxxxxxxxx> On low-memory systems, anti-fragmentation gets disabled as there is nothing it can do and it would just incur overhead shuffling pages between lists constantly. Currently the check is made in the free page fast path for every page. This patch moves it to a slow path. On machines with low memory, there will be small amount of additional overhead as pages get shuffled between lists but it should quickly settle. Signed-off-by: Mel Gorman <mel@xxxxxxxxx> Reviewed-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mmzone.h | 3 --- mm/page_alloc.c | 4 ++++ 2 files changed, 4 insertions(+), 3 deletions(-) diff -puN include/linux/mmzone.h~page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath include/linux/mmzone.h --- a/include/linux/mmzone.h~page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath +++ a/include/linux/mmzone.h @@ -50,9 +50,6 @@ extern int page_group_by_mobility_disabl static inline int get_pageblock_migratetype(struct page *page) { - if (unlikely(page_group_by_mobility_disabled)) - return MIGRATE_UNMOVABLE; - return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end); } diff -puN mm/page_alloc.c~page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath mm/page_alloc.c --- a/mm/page_alloc.c~page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath +++ a/mm/page_alloc.c @@ -172,6 +172,10 @@ int page_group_by_mobility_disabled __re static void set_pageblock_migratetype(struct page *page, int migratetype) { + + if (unlikely(page_group_by_mobility_disabled)) + migratetype = MIGRATE_UNMOVABLE; + set_pageblock_flags_group(page, (unsigned long)migratetype, PB_migrate, PB_migrate_end); } _ Patches currently in -mm which might be from mel@xxxxxxxxx are vmscan-low-order-lumpy-reclaim-also-should-use-pageout_io_sync.patch page-allocator-replace-__alloc_pages_internal-with-__alloc_pages_nodemask.patch page-allocator-do-not-sanity-check-order-in-the-fast-path.patch page-allocator-do-not-sanity-check-order-in-the-fast-path-fix.patch page-allocator-do-not-check-numa-node-id-when-the-caller-knows-the-node-is-valid.patch page-allocator-check-only-once-if-the-zonelist-is-suitable-for-the-allocation.patch page-allocator-break-up-the-allocator-entry-point-into-fast-and-slow-paths.patch page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath.patch page-allocator-calculate-the-preferred-zone-for-allocation-only-once.patch page-allocator-calculate-the-preferred-zone-for-allocation-only-once-fix.patch page-allocator-calculate-the-migratetype-for-allocation-only-once.patch page-allocator-calculate-the-alloc_flags-for-allocation-only-once.patch page-allocator-remove-a-branch-by-assuming-__gfp_high-==-alloc_high.patch page-allocator-inline-__rmqueue_smallest.patch page-allocator-inline-buffered_rmqueue.patch page-allocator-inline-__rmqueue_fallback.patch page-allocator-do-not-call-get_pageblock_migratetype-more-than-necessary.patch page-allocator-do-not-disable-interrupts-in-free_page_mlock.patch page-allocator-do-not-setup-zonelist-cache-when-there-is-only-one-node.patch page-allocator-do-not-check-for-compound-pages-during-the-page-allocator-sanity-checks.patch page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark.patch page-allocator-update-nr_free_pages-only-as-necessary.patch page-allocator-get-the-pageblock-migratetype-without-disabling-interrupts.patch page-allocator-use-a-pre-calculated-value-instead-of-num_online_nodes-in-fast-paths.patch page-allocator-slab-use-nr_online_nodes-to-check-for-a-numa-platform.patch add-debugging-aid-for-memory-initialisation-problems.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html