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Commit 293b6a4c authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

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: default avatarChristoph Lameter <cl@linux.com>
Reported-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Dave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 88da03a6

include/linux/vmstat.h

+6 −2
Original line number Diff line number Diff line
@@ -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)