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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-06-10 13:34:41 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-07-22 15:27:30 -0700 |
| commit | 779de6ce54f627f955d4a3d0c5b3dcfaab74fea8 (patch) | |
| tree | 970e26e9d25d2beab184fb7c87e8ff1c5d348023 /kernel/cpu.c | |
| parent | ec90a194ae2cb8b8e9fe4f6f70dd3d4dc0269b4b (diff) | |
| download | lwn-779de6ce54f627f955d4a3d0c5b3dcfaab74fea8.tar.gz lwn-779de6ce54f627f955d4a3d0c5b3dcfaab74fea8.zip | |
cpu: Wait for RCU grace periods concurrently
In kernels built with CONFIG_PREEMPT, _cpu_down() waits for RCU and
RCU-sched grace periods back-to-back, incurring quite a bit more latency
than required. This commit therefore uses the new synchronize_rcu_mult()
to allow waiting for both grace periods concurrently.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 9c9c9fab16cc..d63b062b6267 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -380,14 +380,14 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) * will observe it. * * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might - * not imply sync_sched(), so explicitly call both. + * not imply sync_sched(), so wait for both. * * Do sync before park smpboot threads to take care the rcu boost case. */ -#ifdef CONFIG_PREEMPT - synchronize_sched(); -#endif - synchronize_rcu(); + if (IS_ENABLED(CONFIG_PREEMPT)) + synchronize_rcu_mult(call_rcu, call_rcu_sched); + else + synchronize_rcu(); smpboot_park_threads(cpu); |