From e9bb18c7b95d4dcf8c7f0e14f920ca6f03109e75 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Thu, 14 Nov 2013 14:30:42 -0800 Subject: [PATCH] mm: avoid increase sizeof(struct page) due to split page table lock Alex Thorlton noticed that some massively threaded workloads work poorly, if THP enabled. This patchset fixes this by introducing split page table lock for PMD tables. hugetlbfs is not covered yet. This patchset is based on work by Naoya Horiguchi. : akpm result summary: : : THP off, v3.12-rc2: 18.059261877 seconds time elapsed : THP off, patched: 16.768027318 seconds time elapsed : : THP on, v3.12-rc2: 42.162306788 seconds time elapsed : THP on, patched: 8.397885779 seconds time elapsed : : HUGETLB, v3.12-rc2: 47.574936948 seconds time elapsed : HUGETLB, patched: 19.447481153 seconds time elapsed THP off, v3.12-rc2: ------------------- Performance counter stats for './thp_memscale -c 80 -b 512m' (5 runs): 1037072.835207 task-clock # 57.426 CPUs utilized ( +- 3.59% ) 95,093 context-switches # 0.092 K/sec ( +- 3.93% ) 140 cpu-migrations # 0.000 K/sec ( +- 5.28% ) 10,000,550 page-faults # 0.010 M/sec ( +- 0.00% ) 2,455,210,400,261 cycles # 2.367 GHz ( +- 3.62% ) [83.33%] 2,429,281,882,056 stalled-cycles-frontend # 98.94% frontend cycles idle ( +- 3.67% ) [83.33%] 1,975,960,019,659 stalled-cycles-backend # 80.48% backend cycles idle ( +- 3.88% ) [66.68%] 46,503,296,013 instructions # 0.02 insns per cycle # 52.24 stalled cycles per insn ( +- 3.21% ) [83.34%] 9,278,997,542 branches # 8.947 M/sec ( +- 4.00% ) [83.34%] 89,881,640 branch-misses # 0.97% of all branches ( +- 1.17% ) [83.33%] 18.059261877 seconds time elapsed ( +- 2.65% ) THP on, v3.12-rc2: ------------------ Performance counter stats for './thp_memscale -c 80 -b 512m' (5 runs): 3114745.395974 task-clock # 73.875 CPUs utilized ( +- 1.84% ) 267,356 context-switches # 0.086 K/sec ( +- 1.84% ) 99 cpu-migrations # 0.000 K/sec ( +- 1.40% ) 58,313 page-faults # 0.019 K/sec ( +- 0.28% ) 7,416,635,817,510 cycles # 2.381 GHz ( +- 1.83% ) [83.33%] 7,342,619,196,993 stalled-cycles-frontend # 99.00% frontend cycles idle ( +- 1.88% ) [83.33%] 6,267,671,641,967 stalled-cycles-backend # 84.51% backend cycles idle ( +- 2.03% ) [66.67%] 117,819,935,165 instructions # 0.02 insns per cycle # 62.32 stalled cycles per insn ( +- 4.39% ) [83.34%] 28,899,314,777 branches # 9.278 M/sec ( +- 4.48% ) [83.34%] 71,787,032 branch-misses # 0.25% of all branches ( +- 1.03% ) [83.33%] 42.162306788 seconds time elapsed ( +- 1.73% ) HUGETLB, v3.12-rc2: ------------------- Performance counter stats for './thp_memscale_hugetlbfs -c 80 -b 512M' (5 runs): 2588052.787264 task-clock # 54.400 CPUs utilized ( +- 3.69% ) 246,831 context-switches # 0.095 K/sec ( +- 4.15% ) 138 cpu-migrations # 0.000 K/sec ( +- 5.30% ) 21,027 page-faults # 0.008 K/sec ( +- 0.01% ) 6,166,666,307,263 cycles # 2.383 GHz ( +- 3.68% ) [83.33%] 6,086,008,929,407 stalled-cycles-frontend # 98.69% frontend cycles idle ( +- 3.77% ) [83.33%] 5,087,874,435,481 stalled-cycles-backend # 82.51% backend cycles idle ( +- 4.41% ) [66.67%] 133,782,831,249 instructions # 0.02 insns per cycle # 45.49 stalled cycles per insn ( +- 4.30% ) [83.34%] 34,026,870,541 branches # 13.148 M/sec ( +- 4.24% ) [83.34%] 68,670,942 branch-misses # 0.20% of all branches ( +- 3.26% ) [83.33%] 47.574936948 seconds time elapsed ( +- 2.09% ) THP off, patched: ----------------- Performance counter stats for './thp_memscale -c 80 -b 512m' (5 runs): 943301.957892 task-clock # 56.256 CPUs utilized ( +- 3.01% ) 86,218 context-switches # 0.091 K/sec ( +- 3.17% ) 121 cpu-migrations # 0.000 K/sec ( +- 6.64% ) 10,000,551 page-faults # 0.011 M/sec ( +- 0.00% ) 2,230,462,457,654 cycles # 2.365 GHz ( +- 3.04% ) [83.32%] 2,204,616,385,805 stalled-cycles-frontend # 98.84% frontend cycles idle ( +- 3.09% ) [83.32%] 1,778,640,046,926 stalled-cycles-backend # 79.74% backend cycles idle ( +- 3.47% ) [66.69%] 45,995,472,617 instructions # 0.02 insns per cycle # 47.93 stalled cycles per insn ( +- 2.51% ) [83.34%] 9,179,700,174 branches # 9.731 M/sec ( +- 3.04% ) [83.35%] 89,166,529 branch-misses # 0.97% of all branches ( +- 1.45% ) [83.33%] 16.768027318 seconds time elapsed ( +- 2.47% ) THP on, patched: ---------------- Performance counter stats for './thp_memscale -c 80 -b 512m' (5 runs): 458793.837905 task-clock # 54.632 CPUs utilized ( +- 0.79% ) 41,831 context-switches # 0.091 K/sec ( +- 0.97% ) 98 cpu-migrations # 0.000 K/sec ( +- 1.66% ) 57,829 page-faults # 0.126 K/sec ( +- 0.62% ) 1,077,543,336,716 cycles # 2.349 GHz ( +- 0.81% ) [83.33%] 1,067,403,802,964 stalled-cycles-frontend # 99.06% frontend cycles idle ( +- 0.87% ) [83.33%] 864,764,616,143 stalled-cycles-backend # 80.25% backend cycles idle ( +- 0.73% ) [66.68%] 16,129,177,440 instructions # 0.01 insns per cycle # 66.18 stalled cycles per insn ( +- 7.94% ) [83.35%] 3,618,938,569 branches # 7.888 M/sec ( +- 8.46% ) [83.36%] 33,242,032 branch-misses # 0.92% of all branches ( +- 2.02% ) [83.32%] 8.397885779 seconds time elapsed ( +- 0.18% ) HUGETLB, patched: ----------------- Performance counter stats for './thp_memscale_hugetlbfs -c 80 -b 512M' (5 runs): 395353.076837 task-clock # 20.329 CPUs utilized ( +- 8.16% ) 55,730 context-switches # 0.141 K/sec ( +- 5.31% ) 138 cpu-migrations # 0.000 K/sec ( +- 4.24% ) 21,027 page-faults # 0.053 K/sec ( +- 0.00% ) 930,219,717,244 cycles # 2.353 GHz ( +- 8.21% ) [83.32%] 914,295,694,103 stalled-cycles-frontend # 98.29% frontend cycles idle ( +- 8.35% ) [83.33%] 704,137,950,187 stalled-cycles-backend # 75.70% backend cycles idle ( +- 9.16% ) [66.69%] 30,541,538,385 instructions # 0.03 insns per cycle # 29.94 stalled cycles per insn ( +- 3.98% ) [83.35%] 8,415,376,631 branches # 21.286 M/sec ( +- 3.61% ) [83.36%] 32,645,478 branch-misses # 0.39% of all branches ( +- 3.41% ) [83.32%] 19.447481153 seconds time elapsed ( +- 2.00% ) This patch (of 11): CONFIG_GENERIC_LOCKBREAK increases sizeof(spinlock_t) to 8 bytes. It leads to increase sizeof(struct page) by 4 bytes on 32-bit system if split page table lock is in use, since page->ptl shares space in union with longs and pointers. Let's disable split page table lock on 32-bit systems with GENERIC_LOCKBREAK enabled. Signed-off-by: Kirill A. Shutemov Cc: Alex Thorlton Cc: Ingo Molnar Cc: Naoya Horiguchi Cc: "Eric W . Biederman" Cc: "Paul E . McKenney" Cc: Al Viro Cc: Andi Kleen Cc: Andrea Arcangeli Cc: Dave Hansen Cc: Dave Jones Cc: David Howells Cc: Frederic Weisbecker Cc: Johannes Weiner Cc: Kees Cook Cc: Mel Gorman Cc: Michael Kerrisk Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Rik van Riel Cc: Robin Holt Cc: Sedat Dilek Cc: Srikar Dronamraju Cc: Thomas Gleixner Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/Kconfig b/mm/Kconfig index 3f4ffda152bb..c28d247e524a 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -219,6 +219,7 @@ config SPLIT_PTLOCK_CPUS default "999999" if ARM && !CPU_CACHE_VIPT default "999999" if PARISC && !PA20 default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC + default "999999" if !64BIT && GENERIC_LOCKBREAK default "4" # -- 2.20.1