From 74f44822097c665041010994502b5971d6cd9f04 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 28 Jun 2021 19:42:24 -0700 Subject: mm/page_alloc: introduce vm.percpu_pagelist_high_fraction This introduces a new sysctl vm.percpu_pagelist_high_fraction. It is similar to the old vm.percpu_pagelist_fraction. The old sysctl increased both pcp->batch and pcp->high with the higher pcp->high potentially reducing zone->lock contention. However, the higher pcp->batch value also potentially increased allocation latency while the PCP was refilled. This sysctl only adjusts pcp->high so that zone->lock contention is potentially reduced but allocation latency during a PCP refill remains the same. # grep -E "high:|batch" /proc/zoneinfo | tail -2 high: 649 batch: 63 # sysctl vm.percpu_pagelist_high_fraction=8 # grep -E "high:|batch" /proc/zoneinfo | tail -2 high: 35071 batch: 63 # sysctl vm.percpu_pagelist_high_fraction=64 high: 4383 batch: 63 # sysctl vm.percpu_pagelist_high_fraction=0 high: 649 batch: 63 [mgorman@techsingularity.net: fix documentation] Link: https://lkml.kernel.org/r/20210528151010.GQ30378@techsingularity.net Link: https://lkml.kernel.org/r/20210525080119.5455-7-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Dave Hansen Acked-by: Vlastimil Babka Cc: Hillf Danton Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 51213c33171e..69d925f1e5da 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2908,6 +2908,14 @@ static struct ctl_table vm_table[] = { .extra1 = SYSCTL_ONE, .extra2 = &one_thousand, }, + { + .procname = "percpu_pagelist_high_fraction", + .data = &percpu_pagelist_high_fraction, + .maxlen = sizeof(percpu_pagelist_high_fraction), + .mode = 0644, + .proc_handler = percpu_pagelist_high_fraction_sysctl_handler, + .extra1 = SYSCTL_ZERO, + }, { .procname = "page_lock_unfairness", .data = &sysctl_page_lock_unfairness, -- cgit v1.2.3