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authorNathan Lynch <ntl@pobox.com>2009-04-08 19:45:12 -0500
committerIngo Molnar <mingo@elte.hu>2009-04-09 07:37:02 +0200
commite3c8ca8336707062f3f7cb1cd7e6b3c753baccdd (patch)
tree281917ab686d2e2a9e1a3996f729fbe97037de97 /include
parent01fad98a1f1d3b38adcbab4bd97f7f4cb983ffb5 (diff)
downloadlinux-linaro-e3c8ca8336707062f3f7cb1cd7e6b3c753baccdd.tar.gz
sched: do not count frozen tasks toward load
Freezing tasks via the cgroup freezer causes the load average to climb because the freezer's current implementation puts frozen tasks in uninterruptible sleep (D state). Some applications which perform job-scheduling functions consult the load average when making decisions. If a cgroup is frozen, the load average does not provide a useful measure of the system's utilization to such applications. This is especially inconvenient if the job scheduler employs the cgroup freezer as a mechanism for preempting low priority jobs. Contrast this with using SIGSTOP for the same purpose: the stopped tasks do not count toward system load. Change task_contributes_to_load() to return false if the task is frozen. This results in /proc/loadavg behavior that better meets users' expectations. Signed-off-by: Nathan Lynch <ntl@pobox.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Nigel Cunningham <nigel@tuxonice.net> Tested-by: Nigel Cunningham <nigel@tuxonice.net> Cc: <stable@kernel.org> Cc: containers@lists.linux-foundation.org Cc: linux-pm@lists.linux-foundation.org Cc: Matt Helsley <matthltc@us.ibm.com> LKML-Reference: <20090408194512.47a99b95@manatee.lan> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 98e1fe51601..b4c38bc8049 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -205,7 +205,8 @@ extern unsigned long long time_sync_thresh;
#define task_is_stopped_or_traced(task) \
((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
#define task_contributes_to_load(task) \
- ((task->state & TASK_UNINTERRUPTIBLE) != 0)
+ ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
+ (task->flags & PF_FROZEN) == 0)
#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)