ksm: keep quiet while list empty

ksm_scan_thread already sleeps in wait_event_interruptible until setting
ksm_run activates it; but if there's nothing on its list to look at, i.e.
nobody has yet said madvise MADV_MERGEABLE, it's a shame to be clocking
up system time and full_scans: ksmd_should_run added to check that too.

And move the mutex_lock out around it: the new counts showed that when
ksm_run is stopped, a little work often got done afterwards, because it
had been read before taking the mutex.

Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Izik Eidus <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions