From 293b6a4c875c3b49853bff7de99954f49f59aa75 Mon Sep 17 00:00:00 2001
From: Christoph Lameter <cl@linux.com>
Date: Mon, 7 Apr 2014 15:39:43 -0700
Subject: [PATCH] vmstat: use raw_cpu_ops to avoid false positives on
preemption checks
vm counters are allowed to be racy. Use raw_cpu_ops to avoid the
local_irq_disable overhead and to avoid preemption checks which will be
added to the __this_cpu operations.
[akpm@linux-foundation.org: Add comment. Again.]
Signed-off-by: Christoph Lameter <cl@linux.com>
Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/vmstat.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index ea4476157e00..45c9cd1daf7a 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -27,9 +27,13 @@ struct vm_event_state {
DECLARE_PER_CPU(struct vm_event_state, vm_event_states);
+/*
+ * vm counters are allowed to be racy. Use raw_cpu_ops to avoid the
+ * local_irq_disable overhead.
+ */
static inline void __count_vm_event(enum vm_event_item item)
{
- __this_cpu_inc(vm_event_states.event[item]);
+ raw_cpu_inc(vm_event_states.event[item]);
}
static inline void count_vm_event(enum vm_event_item item)
@@ -39,7 +43,7 @@ static inline void count_vm_event(enum vm_event_item item)
static inline void __count_vm_events(enum vm_event_item item, long delta)
{
- __this_cpu_add(vm_event_states.event[item], delta);
+ raw_cpu_add(vm_event_states.event[item], delta);
}
static inline void count_vm_events(enum vm_event_item item, long delta)
--
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