On Tue, 2009-12-15 at 09:58 -0500, Rik van Riel wrote:On 12/15/2009 12:32 AM, Mike Galbraith wrote:On Tue, 2009-12-15 at 09:45 +0900, KOSAKI Motohiro wrote:On 12/14/2009 07:30 AM, KOSAKI Motohiro wrote:if we don't use exclusive queue, wake_up() function wake _all_ waited
task. This is simply cpu wasting.
Signed-off-by: KOSAKI Motohiro<kosaki.motohiro@xxxxxxxxxxxxxx>
if (zone_watermark_ok(zone, sc->order, low_wmark_pages(zone),
0, 0)) {
- wake_up(wq);
+ wake_up_all(wq);
finish_wait(wq,&wait);
sc->nr_reclaimed += sc->nr_to_reclaim;
return -ERESTARTSYS;
I believe we want to wake the processes up one at a time
here.
Actually, wake_up() and wake_up_all() aren't different so much.
Although we use wake_up(), the task wake up next task before
try to alloate memory. then, it's similar to wake_up_all().
That is a good point. Maybe processes need to wait a little
in this if() condition, before the wake_up(). That would give
the previous process a chance to allocate memory and we can
avoid waking up too many processes.
Pondering, I think I'd at least wake NR_CPUS. If there's not enough to
go round, oh darn, but if there is, you have full utilization quicker.