tree f39e4a9b845e0bdf8f6b222ca718f155437e5b63
parent 26465d3ea5a62d59efb3796b9e0e2b0656d02cb1
author Hugh Dickins <hugh.dickins@tiscali.co.uk> 1253577734 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1253629052 -0700

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 <hugh.dickins@tiscali.co.uk>
Acked-by: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>