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authorMichael J Wang <mjwang@broadcom.com>2012-03-19 22:26:19 +0000
committerIngo Molnar <mingo@kernel.org>2012-03-27 14:52:12 +0200
commit1b028abc779b67b699daff55e27d2432f8d92666 (patch)
tree0b6deda71cb6ee5a17773716912665b0ad8ddabc /kernel/sched/rt.c
parent2baab4e90495ebc9826c93f79d74d6e60a828d24 (diff)
downloadlinux-1b028abc779b67b699daff55e27d2432f8d92666.tar.bz2
sched/rt: Improve pick_next_highest_task_rt()
Avoid extra work by continuing on to the next rt_rq if the highest prio task in current rt_rq is the same priority as our candidate task. More detailed explanation: if next is not NULL, then we have found a candidate task, and its priority is next->prio. Now we are looking for an even higher priority task in the other rt_rq's. idx is the highest priority in the current candidate rt_rq. In the current 3.3 code, if idx is equal to next->prio, we would start scanning the tasks in that rt_rq and replace the current candidate task with a task from that rt_rq. But the new task would only have a priority that is equal to our previous candidate task, so we have not advanced our goal of finding a higher prio task. So we should avoid the extra work by continuing on to the next rt_rq if idx is equal to next->prio. Signed-off-by: Michael J Wang <mjwang@broadcom.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/2EF88150C0EF2C43A218742ED384C1BC0FC83D6B@IRVEXCHMB08.corp.ad.broadcom.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/rt.c')
-rw-r--r--kernel/sched/rt.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index b60dad720173..44af55e6d5d0 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1428,7 +1428,7 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
next_idx:
if (idx >= MAX_RT_PRIO)
continue;
- if (next && next->prio < idx)
+ if (next && next->prio <= idx)
continue;
list_for_each_entry(rt_se, array->queue + idx, run_list) {
struct task_struct *p;