linux/mm/page_alloc.c, branch v3.13

mm: page_alloc: revert NUMA aspect of fair allocation policy

2013-12-20T20:19:18Z

Commit 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy") meant to bring aging fairness among zones in system, but it was overzealous and badly regressed basic workloads on NUMA systems. Due to the way kswapd and page allocator interacts, we still want to make sure that all zones in any given node are used equally for all allocations to maximize memory utilization and prevent thrashing on the highest zone in the node. While the same principle applies to NUMA nodes - memory utilization is obviously improved by spreading allocations throughout all nodes - remote references can be costly and so many workloads prefer locality over memory utilization. The original change assumed that zone_reclaim_mode would be a good enough predictor for that, but it turned out to be as indicative as a coin flip. Revert the NUMA aspect of the fairness until we can find a proper way to make it configurable and agree on a sane default. Signed-off-by: Johannes Weiner Reviewed-by: Michal Hocko Signed-off-by: Mel Gorman Cc: # 3.12 Signed-off-by: Linus Torvalds

Revert "mm: page_alloc: exclude unreclaimable allocations from zone fairness policy"

2013-12-20T20:19:18Z

This reverts commit 73f038b863df. The NUMA behaviour of this patch is less than ideal. An alternative approch is to interleave allocations only within local zones which is implemented in the next patch. Cc: stable@vger.kernel.org Signed-off-by: Mel Gorman Signed-off-by: Linus Torvalds

mm: page_alloc: exclude unreclaimable allocations from zone fairness policy

2013-12-19T03:04:51Z

Dave Hansen noted a regression in a microbenchmark that loops around open() and close() on an 8-node NUMA machine and bisected it down to commit 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy"). That change forces the slab allocations of the file descriptor to spread out to all 8 nodes, causing remote references in the page allocator and slab. The round-robin policy is only there to provide fairness among memory allocations that are reclaimed involuntarily based on pressure in each zone. It does not make sense to apply it to unreclaimable kernel allocations that are freed manually, in this case instantly after the allocation, and incur the remote reference costs twice for no reason. Only round-robin allocations that are usually freed through page reclaim or slab shrinking. Bisected by Dave Hansen. Signed-off-by: Johannes Weiner Cc: Dave Hansen Cc: Mel Gorman Reviewed-by: Rik van Riel Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: fix comment in zlc_setup()

2013-11-13T03:09:11Z

Signed-off-by: Zhi Yong Wu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: __rmqueue_fallback() should respect pageblock type

2013-11-13T03:09:10Z

When __rmqueue_fallback() doesn't find a free block with the required size it splits a larger page and puts the rest of the page onto the free list. But it has one serious mistake. When putting back, __rmqueue_fallback() always use start_migratetype if type is not CMA. However, __rmqueue_fallback() is only called when all of the start_migratetype queue is empty. That said, __rmqueue_fallback always puts back memory to the wrong queue except try_to_steal_freepages() changed pageblock type (i.e. requested size is smaller than half of page block). The end result is that the antifragmentation framework increases fragmenation instead of decreasing it. Mel's original anti fragmentation does the right thing. But commit 47118af076f6 ("mm: mmzone: MIGRATE_CMA migration type added") broke it. This patch restores sane and old behavior. It also removes an incorrect comment which was introduced by commit fef903efcf0c ("mm/page_alloc.c: restructure free-page stealing code and fix a bug"). Signed-off-by: KOSAKI Motohiro Cc: Mel Gorman Cc: Michal Nazarewicz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: get rid of unnecessary overhead of trace_mm_page_alloc_extfrag()

2013-11-13T03:09:10Z

In general, every tracepoint should be zero overhead if it is disabled. However, trace_mm_page_alloc_extfrag() is one of exception. It evaluate "new_type == start_migratetype" even if tracepoint is disabled. However, the code can be moved into tracepoint's TP_fast_assign() and TP_fast_assign exist exactly such purpose. This patch does it. Signed-off-by: KOSAKI Motohiro Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: fix page_group_by_mobility_disabled breakage

2013-11-13T03:09:09Z

Currently, set_pageblock_migratetype() screws up MIGRATE_CMA and MIGRATE_ISOLATE if page_group_by_mobility_disabled is true. It rewrites the argument to MIGRATE_UNMOVABLE and we lost these attribute. The problem was introduced by commit 49255c619fbd ("page allocator: move check for disabled anti-fragmentation out of fastpath"). So a 4 year old issue may mean that nobody uses page_group_by_mobility_disabled. But anyway, this patch fixes the problem. Signed-off-by: KOSAKI Motohiro Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: remove unused marco LONG_ALIGN

2013-11-13T03:09:07Z

Signed-off-by: Zhang Yanfei Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: add a helper function to check may oom condition

2013-11-13T03:09:04Z

Use helper function to check if we need to deal with oom condition. Signed-off-by: Qiang Huang Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: use populated_zone() instead of if(zone->present_pages)

2013-11-13T03:09:04Z

Use "if (zone->present_pages)" instead of "if (zone->present_pages)". Simplify the code, no functional change. Signed-off-by: Xishi Qiu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds