diff options
author | Peter Zijlstra <peterz@infradead.org> | 2014-02-14 06:25:08 -0500 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2014-02-27 06:41:02 -0500 |
commit | 37e117c07b89194aae7062bc63bde1104c03db02 (patch) | |
tree | 770312bf789e367b8f2102e9f8de743f05efeeac /kernel/trace/ring_buffer_benchmark.c | |
parent | 06d50c65b1043b166d102accc081093f79d8f7e5 (diff) |
sched: Guarantee task priority in pick_next_task()
Michael spotted that the idle_balance() push down created a task
priority problem.
Previously, when we called idle_balance() before pick_next_task() it
wasn't a problem when -- because of the rq->lock droppage -- an rt/dl
task slipped in.
Similarly for pre_schedule(), rt pre-schedule could have a dl task
slip in.
But by pulling it into the pick_next_task() loop, we'll not try a
higher task priority again.
Cure this by creating a re-start condition in pick_next_task(); and
triggering this from pick_next_task_{rt,fair}().
It also fixes a live-lock where we get stuck in pick_next_task_fair()
due to idle_balance() seeing !0 nr_running but there not actually
being any fair tasks about.
Reported-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Fixes: 38033c37faab ("sched: Push down pre_schedule() and idle_balance()")
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140224121218.GR15586@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/trace/ring_buffer_benchmark.c')
0 files changed, 0 insertions, 0 deletions