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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2011-07-05 10:56:32 +0200
committerIngo Molnar <mingo@elte.hu>2011-07-05 11:28:18 +0200
commite4c2fb0d5776b58049d2556b456144a4db3fe5a9 (patch)
tree04cebbb24f524408728492cfeb396d66aa6127e4
parentcd62287e364c0d15d517c6ced4e4808b54711475 (diff)
downloadlinux-e4c2fb0d5776b58049d2556b456144a4db3fe5a9.tar.bz2
sched: Disable (revert) SCHED_LOAD_SCALE increase
Alex reported that commit c8b281161df ("sched: Increase SCHED_LOAD_SCALE resolution") caused a power usage regression under light load as it increases the number of load-balance operations and keeps idle cpus from staying idle. Time has run out to find the root cause for this release so disable the feature for v3.0 until we can figure out what causes the problem. Reported-by: "Alex, Shi" <alex.shi@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Nikhil Rao <ncrao@google.com> Cc: Ming Lei <tom.leiming@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-m4onxn0sxnyn5iz9o88eskc3@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/sched.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a837b20ba190..496770a96487 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -808,7 +808,7 @@ enum cpu_idle_type {
* when BITS_PER_LONG <= 32 are pretty high and the returns do not justify the
* increased costs.
*/
-#if BITS_PER_LONG > 32
+#if 0 /* BITS_PER_LONG > 32 -- currently broken: it increases power usage under light load */
# define SCHED_LOAD_RESOLUTION 10
# define scale_load(w) ((w) << SCHED_LOAD_RESOLUTION)
# define scale_load_down(w) ((w) >> SCHED_LOAD_RESOLUTION)