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| author | Peng Liu <iwtbavbm@gmail.com> | 2020-10-08 17:48:46 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-10-29 11:00:28 +0100 |
| commit | 26762423a2664692de2bcccc9de684a5ac105e23 (patch) | |
| tree | 0228fd08fc8c15d1c1ebc2c5e96a7e42dd33cf91 /kernel/sched/deadline.c | |
| parent | sched/fair: Improve the accuracy of sched_stat_wait statistics (diff) | |
| download | linux-26762423a2664692de2bcccc9de684a5ac105e23.tar.xz linux-26762423a2664692de2bcccc9de684a5ac105e23.zip | |
sched/deadline: Optimize sched_dl_global_validate()
Under CONFIG_SMP, dl_bw is per root domain, but not per CPU.
When checking or updating dl_bw, currently iterating every CPU is
overdoing, just need iterate each root domain once.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Peng Liu <iwtbavbm@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/78d21ee792cc48ff79e8cd62a5f26208463684d6.1602171061.git.iwtbavbm@gmail.com
Diffstat (limited to 'kernel/sched/deadline.c')
| -rw-r--r-- | kernel/sched/deadline.c | 39 |
1 files changed, 32 insertions, 7 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index f232305dcefe..98d96d40e202 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -97,6 +97,17 @@ static inline unsigned long dl_bw_capacity(int i) return __dl_bw_capacity(i); } } + +static inline bool dl_bw_visited(int cpu, u64 gen) +{ + struct root_domain *rd = cpu_rq(cpu)->rd; + + if (rd->visit_gen == gen) + return true; + + rd->visit_gen = gen; + return false; +} #else static inline struct dl_bw *dl_bw_of(int i) { @@ -112,6 +123,11 @@ static inline unsigned long dl_bw_capacity(int i) { return SCHED_CAPACITY_SCALE; } + +static inline bool dl_bw_visited(int cpu, u64 gen) +{ + return false; +} #endif static inline @@ -2535,11 +2551,15 @@ const struct sched_class dl_sched_class .update_curr = update_curr_dl, }; +/* Used for dl_bw check and update, used under sched_rt_handler()::mutex */ +static u64 dl_generation; + int sched_dl_global_validate(void) { u64 runtime = global_rt_runtime(); u64 period = global_rt_period(); u64 new_bw = to_ratio(period, runtime); + u64 gen = ++dl_generation; struct dl_bw *dl_b; int cpu, ret = 0; unsigned long flags; @@ -2548,13 +2568,13 @@ int sched_dl_global_validate(void) * Here we want to check the bandwidth not being set to some * value smaller than the currently allocated bandwidth in * any of the root_domains. - * - * FIXME: Cycling on all the CPUs is overdoing, but simpler than - * cycling on root_domains... Discussion on different/better - * solutions is welcome! */ for_each_possible_cpu(cpu) { rcu_read_lock_sched(); + + if (dl_bw_visited(cpu, gen)) + goto next; + dl_b = dl_bw_of(cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); @@ -2562,6 +2582,7 @@ int sched_dl_global_validate(void) ret = -EBUSY; raw_spin_unlock_irqrestore(&dl_b->lock, flags); +next: rcu_read_unlock_sched(); if (ret) @@ -2587,6 +2608,7 @@ static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq) void sched_dl_do_global(void) { u64 new_bw = -1; + u64 gen = ++dl_generation; struct dl_bw *dl_b; int cpu; unsigned long flags; @@ -2597,11 +2619,14 @@ void sched_dl_do_global(void) if (global_rt_runtime() != RUNTIME_INF) new_bw = to_ratio(global_rt_period(), global_rt_runtime()); - /* - * FIXME: As above... - */ for_each_possible_cpu(cpu) { rcu_read_lock_sched(); + + if (dl_bw_visited(cpu, gen)) { + rcu_read_unlock_sched(); + continue; + } + dl_b = dl_bw_of(cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); |