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authorPeter Zijlstra <peterz@infradead.org>2013-10-07 11:29:21 +0100
committerIngo Molnar <mingo@kernel.org>2013-10-09 14:47:47 +0200
commit8c8a743c5087bac9caac8155b8f3b367e75cdd0b (patch)
treed5cc5c5f4368cf7d3deb627388c869dbea2e83f2 /mm/memory.c
parent90572890d202527c366aa9489b32404e88a7c020 (diff)
downloadlinux-8c8a743c5087bac9caac8155b8f3b367e75cdd0b.tar.bz2
sched/numa: Use {cpu, pid} to create task groups for shared faults
While parallel applications tend to align their data on the cache boundary, they tend not to align on the page or THP boundary. Consequently tasks that partition their data can still "false-share" pages presenting a problem for optimal NUMA placement. This patch uses NUMA hinting faults to chain tasks together into numa_groups. As well as storing the NID a task was running on when accessing a page a truncated representation of the faulting PID is stored. If subsequent faults are from different PIDs it is reasonable to assume that those two tasks share a page and are candidates for being grouped together. Note that this patch makes no scheduling decisions based on the grouping information. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-44-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 5162e6d0d652..c57efa25cdbb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2719,6 +2719,14 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
get_page(dirty_page);
reuse:
+ /*
+ * Clear the pages cpupid information as the existing
+ * information potentially belongs to a now completely
+ * unrelated process.
+ */
+ if (old_page)
+ page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1);
+
flush_cache_page(vma, address, pte_pfn(orig_pte));
entry = pte_mkyoung(orig_pte);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);