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vmstat: use raw_cpu_ops to avoid false positives on preemption checks

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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>
This commit is contained in:
Christoph Lameter 2014-04-07 15:39:43 -07:00 committed by Linus Torvalds
parent 88da03a676
commit 293b6a4c87
1 changed files with 6 additions and 2 deletions
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8
include/linux/vmstat.h
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@ -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)