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| author | Hailong Liu <liu.hailong6@zte.com.cn> | 2018-07-18 08:46:55 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-05 09:26:29 +0200 |
| commit | d35aab9df15a514b3efc69f92011625cd934df95 (patch) | |
| tree | 596b3d0b7cfdc6774a91d1a75e093e67a43a2fe1 /kernel/sched | |
| parent | 0ba83f87c3f1a16dab4a55ca52c57e59486c9917 (diff) | |
sched/rt: Restore rt_runtime after disabling RT_RUNTIME_SHARE
[ Upstream commit f3d133ee0a17d5694c6f21873eec9863e11fa423 ]
NO_RT_RUNTIME_SHARE feature is used to prevent a CPU borrow enough
runtime with a spin-rt-task.
However, if RT_RUNTIME_SHARE feature is enabled and rt_rq has borrowd
enough rt_runtime at the beginning, rt_runtime can't be restored to
its initial bandwidth rt_runtime after we disable RT_RUNTIME_SHARE.
E.g. on my PC with 4 cores, procedure to reproduce:
1) Make sure RT_RUNTIME_SHARE is enabled
cat /sys/kernel/debug/sched_features
GENTLE_FAIR_SLEEPERS START_DEBIT NO_NEXT_BUDDY LAST_BUDDY
CACHE_HOT_BUDDY WAKEUP_PREEMPTION NO_HRTICK NO_DOUBLE_TICK
LB_BIAS NONTASK_CAPACITY TTWU_QUEUE NO_SIS_AVG_CPU SIS_PROP
NO_WARN_DOUBLE_CLOCK RT_PUSH_IPI RT_RUNTIME_SHARE NO_LB_MIN
ATTACH_AGE_LOAD WA_IDLE WA_WEIGHT WA_BIAS
2) Start a spin-rt-task
./loop_rr &
3) set affinity to the last cpu
taskset -p 8 $pid_of_loop_rr
4) Observe that last cpu have borrowed enough runtime.
cat /proc/sched_debug | grep rt_runtime
.rt_runtime : 950.000000
.rt_runtime : 900.000000
.rt_runtime : 950.000000
.rt_runtime : 1000.000000
5) Disable RT_RUNTIME_SHARE
echo NO_RT_RUNTIME_SHARE > /sys/kernel/debug/sched_features
6) Observe that rt_runtime can not been restored
cat /proc/sched_debug | grep rt_runtime
.rt_runtime : 950.000000
.rt_runtime : 900.000000
.rt_runtime : 950.000000
.rt_runtime : 1000.000000
This patch help to restore rt_runtime after we disable
RT_RUNTIME_SHARE.
Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn>
Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1531874815-39357-1-git-send-email-liu.hailong6@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/rt.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index bba2217652ff..cb9a5b8532fa 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -837,6 +837,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) * can be time-consuming. Try to avoid it when possible. */ raw_spin_lock(&rt_rq->rt_runtime_lock); + if (!sched_feat(RT_RUNTIME_SHARE) && rt_rq->rt_runtime != RUNTIME_INF) + rt_rq->rt_runtime = rt_b->rt_runtime; skip = !rt_rq->rt_time && !rt_rq->rt_nr_running; raw_spin_unlock(&rt_rq->rt_runtime_lock); if (skip) |