diff mbox series

[v5,2/9] task_isolation: vmstat: add vmstat_idle function

Message ID 6ac7143e5038614e3950636456cef67b5bc0c9e4.camel@marvell.com
State New
Headers show
Series "Task_isolation" mode | expand

Commit Message

Alex Belits Nov. 23, 2020, 5:56 p.m. UTC 
From: Chris Metcalf <cmetcalf@mellanox.com>


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@mellanox.com>

Signed-off-by: Alex Belits <abelits@marvell.com>

---
 include/linux/vmstat.h |  2 ++
 mm/vmstat.c            | 10 ++++++++++
 2 files changed, 12 insertions(+)

-- 
2.20.1

Comments

Thomas Gleixner Nov. 23, 2020, 9:49 p.m. UTC | #1 
On Mon, Nov 23 2020 at 17:56, Alex Belits wrote:
> 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.

A changelog has to explain _WHY_ this change is necessary and not _WHAT_
the patch is doing.

Thanks,

        tglx
diff mbox series

Patch

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 300ce6648923..24392a957cfc 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -285,6 +285,7 @@  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);
 
@@ -393,6 +394,7 @@  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 43999caf47a4..5b0ad7ed65f7 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1945,6 +1945,16 @@  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