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authorSrikar Dronamraju <srikar@linux.vnet.ibm.com>2014-04-07 15:37:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-07 16:35:58 -0700
commit834a964a098e7726fc296d7cd8f65ed3eeedd412 (patch)
tree8d7ed993d4ccc002ffaa9980eef1ce5ccc687542 /include
parent85892f196fd8fb22386436f86f2b74104d7005f8 (diff)
downloadlinux-834a964a098e7726fc296d7cd8f65ed3eeedd412.tar.bz2
numa: use LAST_CPUPID_SHIFT to calculate LAST_CPUPID_MASK
LAST_CPUPID_MASK is calculated using LAST_CPUPID_WIDTH. However LAST_CPUPID_WIDTH itself can be 0. (when LAST_CPUPID_NOT_IN_PAGE_FLAGS is set). In such a case LAST_CPUPID_MASK turns out to be 0. But with recent commit 1ae71d0319: (mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS) if LAST_CPUPID_MASK is 0, page_cpupid_xchg_last() and page_cpupid_reset_last() causes page->_last_cpupid to be set to 0. This causes performance regression. Its almost as if numa_balancing is off. Fix LAST_CPUPID_MASK by using LAST_CPUPID_SHIFT instead of LAST_CPUPID_WIDTH. Some performance numbers and perf stats with and without the fix. (3.14-rc6) ---------- numa01 Performance counter stats for '/usr/bin/time -f %e %S %U %c %w -o start_bench.out -a ./numa01': 12,27,462 cs [100.00%] 2,41,957 migrations [100.00%] 1,68,01,713 faults [100.00%] 7,99,35,29,041 cache-misses 98,808 migrate:mm_migrate_pages [100.00%] 1407.690148814 seconds time elapsed numa02 Performance counter stats for '/usr/bin/time -f %e %S %U %c %w -o start_bench.out -a ./numa02': 63,065 cs [100.00%] 14,364 migrations [100.00%] 2,08,118 faults [100.00%] 25,32,59,404 cache-misses 12 migrate:mm_migrate_pages [100.00%] 63.840827219 seconds time elapsed (3.14-rc6 with fix) ------------------- numa01 Performance counter stats for '/usr/bin/time -f %e %S %U %c %w -o start_bench.out -a ./numa01': 9,68,911 cs [100.00%] 1,01,414 migrations [100.00%] 88,38,697 faults [100.00%] 4,42,92,51,042 cache-misses 4,25,060 migrate:mm_migrate_pages [100.00%] 685.965331189 seconds time elapsed numa02 Performance counter stats for '/usr/bin/time -f %e %S %U %c %w -o start_bench.out -a ./numa02': 17,543 cs [100.00%] 2,962 migrations [100.00%] 1,17,843 faults [100.00%] 11,80,61,644 cache-misses 12,358 migrate:mm_migrate_pages [100.00%] 20.380132343 seconds time elapsed Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Liu Ping Fan <pingfank@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6edcea720ddd..abc848412e3c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -695,7 +695,7 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address,
#define ZONES_MASK ((1UL << ZONES_WIDTH) - 1)
#define NODES_MASK ((1UL << NODES_WIDTH) - 1)
#define SECTIONS_MASK ((1UL << SECTIONS_WIDTH) - 1)
-#define LAST_CPUPID_MASK ((1UL << LAST_CPUPID_WIDTH) - 1)
+#define LAST_CPUPID_MASK ((1UL << LAST_CPUPID_SHIFT) - 1)
#define ZONEID_MASK ((1UL << ZONEID_SHIFT) - 1)
static inline enum zone_type page_zonenum(const struct page *page)