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author | 2014-03-06 13:32:01 +0400 | |
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committer | 2014-03-11 12:05:39 +0100 | |
commit | 4c6c4e38c4e9a454889298dcc498174968d14a09 (patch) | |
tree | ffb6a22c1f3a58667b3c745fe055b6dab3065443 /tools/perf/scripts/python/call-graph-from-postgresql.py | |
parent | sched/fair: Push down check for high priority class task into idle_balance() (diff) | |
download | linux-dev-4c6c4e38c4e9a454889298dcc498174968d14a09.tar.xz linux-dev-4c6c4e38c4e9a454889298dcc498174968d14a09.zip |
sched/core: Fix endless loop in pick_next_task()
1) Single cpu machine case.
When rq has only RT tasks, but no one of them can be picked
because of throttling, we enter in endless loop.
pick_next_task_{dl,rt} return NULL.
In pick_next_task_fair() we permanently go to retry
if (rq->nr_running != rq->cfs.h_nr_running)
return RETRY_TASK;
(rq->nr_running is not being decremented when rt_rq becomes
throttled).
No chances to unthrottle any rt_rq or to wake fair here,
because of rq is locked permanently and interrupts are
disabled.
2) In case of SMP this can cause a hang too. Although we unlock
rq in idle_balance(), interrupts are still disabled.
The solution is to check for available tasks in DL and RT
classes instead of checking for sum.
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1394098321.19290.11.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/perf/scripts/python/call-graph-from-postgresql.py')
0 files changed, 0 insertions, 0 deletions