diff options
| author | Tim Chen <tim.c.chen@linux.intel.com> | 2014-12-12 15:38:12 -0800 |
|---|---|---|
| committer | Pat Tjin <pattjin@google.com> | 2017-04-26 18:52:22 +0000 |
| commit | 567b930e04fcf8a40e24067d355a8b4080af3fc7 (patch) | |
| tree | 444d339f26174d0444e4f0e7b77fffc068346645 | |
| parent | 84ae7364326ea759f39d9ed6973de30f21d6090d (diff) | |
BACKPORT: sched/rt: Reduce rq lock contention by eliminating locking of non-feasible targetandroid-o-preview-2_r0.6
This patch adds checks that prevens futile attempts to move rt tasks
to a CPU with active tasks of equal or higher priority.
This reduces run queue lock contention and improves the performance of
a well known OLTP benchmark by 0.7%.
Bug: 37474896
(@joel: One of the hunks in this patch was already applied by Srinath in
commit [1], so dropping that hunk)
[1] commit 89288d853b2a ("sched/rt: Avoid moving rt task if destination
CPU does not run low priority task.")
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shawn Bohrer <sbohrer@rgmadvisors.com>
Cc: Suruchi Kadu <suruchi.a.kadu@intel.com>
Cc: Doug Nelson<doug.nelson@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1421430374.2399.27.camel@schen9-desk2.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Change-Id: I80da92afed2957537e1a64b90144293f74003969
| -rw-r--r-- | kernel/sched/rt.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index f3c02a5fbb41..07dd76ad7311 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1780,6 +1780,16 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq) lowest_rq = cpu_rq(cpu); + if (lowest_rq->rt.highest_prio.curr <= task->prio) { + /* + * Target rq has tasks of equal or higher priority, + * retrying does not release any lock and is unlikely + * to yield a different result. + */ + lowest_rq = NULL; + break; + } + /* if the prio of this runqueue changed, try again */ if (double_lock_balance(rq, lowest_rq)) { /* |