diff mbox series

[v5,1/9] task_isolation: vmstat: add quiet_vmstat_sync function

Message ID 0e07e5bf6f65dc89d263683c81b4a19bcc6d4b60.camel@marvell.com
State Superseded
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>

In commit f01f17d3705b ("mm, vmstat: make quiet_vmstat lighter")
the quiet_vmstat() function became asynchronous, in the sense that
the vmstat work was still scheduled to run on the core when the
function returned.  For task isolation, we need a synchronous
version of the function that guarantees that the vmstat worker
will not run on the core on return from the function.  Add a
quiet_vmstat_sync() function with that semantic.

Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: Alex Belits <abelits@marvell.com>
---
 include/linux/vmstat.h | 2 ++
 mm/vmstat.c            | 9 +++++++++
 2 files changed, 11 insertions(+)

Comments

Thomas Gleixner Nov. 23, 2020, 9:48 p.m. UTC | #1 
Alex,

On Mon, Nov 23 2020 at 17:56, Alex Belits wrote:

why are you insisting on adding 'task_isolation: ' as prefix to every
single patch? That's wrong as I explained before.

The prefix denotes the affected subsystem and 'task_isolation' is _NOT_
a subsystem. It's the project name you are using but the affected code
belongs to the memory management subsystem and if you run

 git log mm/vmstat.c

you might get a hint what the proper prefix is, i.e. 'mm/vmstat: '

> In commit f01f17d3705b ("mm, vmstat: make quiet_vmstat lighter")
> the quiet_vmstat() function became asynchronous, in the sense that
> the vmstat work was still scheduled to run on the core when the
> function returned.  For task isolation, we need a synchronous

This changelog is useless because how should someone not familiar with
the term 'task isolation' figure out what that means?

It's not the reviewers job to figure that out. Again: Go read and adhere
to Documentation/process/*

Aside of that your patches are CR/LF inflicted. Please fix your work
flow and tools.

Thanks,

        tglx
diff mbox series

Patch

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 322dcbfcc933..300ce6648923 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -284,6 +284,7 @@  extern void __dec_zone_state(struct zone *, enum zone_stat_item);
 extern void __dec_node_state(struct pglist_data *, enum node_stat_item);
 
 void quiet_vmstat(void);
+void quiet_vmstat_sync(void);
 void cpu_vm_stats_fold(int cpu);
 void refresh_zone_stat_thresholds(void);
 
@@ -391,6 +392,7 @@  static inline void __dec_node_page_state(struct page *page,
 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 void drain_zonestat(struct zone *zone,
 			struct per_cpu_pageset *pset) { }
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 698bc0bc18d1..43999caf47a4 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1936,6 +1936,15 @@  void quiet_vmstat(void)
 	refresh_cpu_vm_stats(false);
 }
 
+/*
+ * Synchronously quiet vmstat so the work is guaranteed not to run on return.
+ */
+void quiet_vmstat_sync(void)
+{
+	cancel_delayed_work_sync(this_cpu_ptr(&vmstat_work));
+	refresh_cpu_vm_stats(false);
+}
+
 /*
  * Shepherd worker thread that checks the
  * differentials of processors that have their worker