Currently resetting the migrate rate limit is under a spinlock. The spinlock will only serialize the migrate rate limiting and something similar can actually be achieved by a simpler xchg.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM JVMS LAST_PATCH WITH_PATCH %CHANGE 16 25804.1 25355.9 -1.73 1 73413 72812 -0.81 Running SPECjbb2005 on a 16 node machine and comparing bops/JVM JVMS LAST_PATCH WITH_PATCH %CHANGE 8 101748 110199 8.30 1 170818 176303 3.21 (numbers from v1 based on v4.17-rc5) Testcase Time: Min Max Avg StdDev numa01.sh Real: 435.67 707.28 527.49 97.85 numa01.sh Sys: 76.41 231.19 162.49 56.13 numa01.sh User: 38247.36 59033.52 45129.31 7642.69 numa02.sh Real: 60.35 62.09 61.09 0.69 numa02.sh Sys: 15.01 30.20 20.64 5.56 numa02.sh User: 5195.93 5294.82 5240.99 40.55 numa03.sh Real: 752.04 919.89 836.81 63.29 numa03.sh Sys: 115.10 133.35 125.46 7.78 numa03.sh User: 58736.44 70084.26 65103.67 4416.10 numa04.sh Real: 418.43 709.69 512.53 104.17 numa04.sh Sys: 242.99 370.47 297.39 42.20 numa04.sh User: 34916.14 48429.54 38955.65 4928.05 numa05.sh Real: 379.27 434.05 403.70 17.79 numa05.sh Sys: 145.94 344.50 268.72 68.53 numa05.sh User: 32679.32 35449.75 33989.10 913.19 Testcase Time: Min Max Avg StdDev %Change numa01.sh Real: 490.04 774.86 596.26 96.46 -11.5% numa01.sh Sys: 151.52 242.88 184.82 31.71 -12.0% numa01.sh User: 41418.41 60844.59 48776.09 6564.27 -7.47% numa02.sh Real: 60.14 62.94 60.98 1.00 0.180% numa02.sh Sys: 16.11 30.77 21.20 5.28 -2.64% numa02.sh User: 5184.33 5311.09 5228.50 44.24 0.238% numa03.sh Real: 790.95 856.35 826.41 24.11 1.258% numa03.sh Sys: 114.93 118.85 117.05 1.63 7.184% numa03.sh User: 60990.99 64959.28 63470.43 1415.44 2.573% numa04.sh Real: 434.37 597.92 504.87 59.70 1.517% numa04.sh Sys: 237.63 397.40 289.74 55.98 2.640% numa04.sh User: 34854.87 41121.83 38572.52 2615.84 0.993% numa05.sh Real: 386.77 448.90 417.22 22.79 -3.24% numa05.sh Sys: 149.23 379.95 303.04 79.55 -11.3% numa05.sh User: 32951.76 35959.58 34562.18 1034.05 -1.65% Signed-off-by: Srikar Dronamraju <[email protected]> --- Changelog v1->v2: Fix stretch every interval pointed by Peter Zijlstra. include/linux/mmzone.h | 3 --- mm/migrate.c | 20 ++++++++++++++------ mm/page_alloc.c | 1 - 3 files changed, 14 insertions(+), 10 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b0767703..0dbe1d5 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -669,9 +669,6 @@ struct zonelist { struct task_struct *kcompactd; #endif #ifdef CONFIG_NUMA_BALANCING - /* Lock serializing the migrate rate limiting window */ - spinlock_t numabalancing_migrate_lock; - /* Rate limiting time interval */ unsigned long numabalancing_migrate_next_window; diff --git a/mm/migrate.c b/mm/migrate.c index 8c0af0f..c774990 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1868,17 +1868,25 @@ static struct page *alloc_misplaced_dst_page(struct page *page, static bool numamigrate_update_ratelimit(pg_data_t *pgdat, unsigned long nr_pages) { + unsigned long next_window, interval; + + next_window = READ_ONCE(pgdat->numabalancing_migrate_next_window); + interval = msecs_to_jiffies(migrate_interval_millisecs); + /* * Rate-limit the amount of data that is being migrated to a node. * Optimal placement is no good if the memory bus is saturated and * all the time is being spent migrating! */ - if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { - spin_lock(&pgdat->numabalancing_migrate_lock); - pgdat->numabalancing_migrate_nr_pages = 0; - pgdat->numabalancing_migrate_next_window = jiffies + - msecs_to_jiffies(migrate_interval_millisecs); - spin_unlock(&pgdat->numabalancing_migrate_lock); + if (time_after(jiffies, next_window)) { + if (xchg(&pgdat->numabalancing_migrate_nr_pages, 0)) { + do { + next_window += interval; + } while (unlikely(time_after(jiffies, next_window))); + + WRITE_ONCE(pgdat->numabalancing_migrate_next_window, + next_window); + } } if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8a522d2..ff8e730 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6207,7 +6207,6 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat) pgdat_resize_init(pgdat); #ifdef CONFIG_NUMA_BALANCING - spin_lock_init(&pgdat->numabalancing_migrate_lock); pgdat->numabalancing_migrate_nr_pages = 0; pgdat->active_node_migrate = 0; pgdat->numabalancing_migrate_next_window = jiffies; -- 1.8.3.1
