>From 7823be8cd3ba2e66308f334a2e47f60ba7829e0b Mon Sep 17 00:00:00 2001 From: Chris Metcalf <cmetcalf@xxxxxxxxxxxx> Date: Sat, 1 Feb 2020 08:05:45 +0000 Subject: [PATCH 02/13] task_isolation: vmstat: add vmstat_idle function This function checks to see if a vmstat worker is not running, and the vmstat diffs don't require an update. The function is called from the task-isolation code to see if we need to actually do some work to quiet vmstat. Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx> Signed-off-by: Alex Belits <abelits@xxxxxxxxxxx> --- include/linux/vmstat.h | 2 ++ mm/vmstat.c | 10 ++++++++++ 2 files changed, 12 insertions(+) diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index ded16dfd21fa..97bc9ed92036 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -273,6 +273,7 @@ extern void __dec_node_state(struct pglist_data *, enum node_stat_item); void quiet_vmstat(void); void quiet_vmstat_sync(void); +bool vmstat_idle(void); void cpu_vm_stats_fold(int cpu); void refresh_zone_stat_thresholds(void); @@ -376,6 +377,7 @@ static inline void refresh_zone_stat_thresholds(void) { } static inline void cpu_vm_stats_fold(int cpu) { } static inline void quiet_vmstat(void) { } static inline void quiet_vmstat_sync(void) { } +static inline bool vmstat_idle(void) { return true; } static inline void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset) { } diff --git a/mm/vmstat.c b/mm/vmstat.c index 93534f8537ca..f3693ef0a958 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1898,6 +1898,16 @@ void quiet_vmstat_sync(void) refresh_cpu_vm_stats(false); } +/* + * Report on whether vmstat processing is quiesced on the core currently: + * no vmstat worker running and no vmstat updates to perform. + */ +bool vmstat_idle(void) +{ + return !delayed_work_pending(this_cpu_ptr(&vmstat_work)) && + !need_update(smp_processor_id()); +} + /* * Shepherd worker thread that checks the * differentials of processors that have their worker -- 2.26.2