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| author | Shaohua Li <shaohua.li@intel.com> | 2011-06-16 16:02:54 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-09-28 21:36:34 -0700 |
| commit | 1eb521210a8c9823038abe4ddfe8c69e713ec17d (patch) | |
| tree | f9fc70df7c25f80def12aeb231475405043eb1ed /kernel/rcutree_plugin.h | |
| parent | 1f288094807861ec1e48c428d2c49ccf7aaf3767 (diff) | |
| download | lwn-1eb521210a8c9823038abe4ddfe8c69e713ec17d.tar.gz lwn-1eb521210a8c9823038abe4ddfe8c69e713ec17d.zip | |
rcu: Avoid unnecessary self-wakeup of per-CPU kthreads
There are a number of cases where the RCU can find additional work
for the per-CPU kthread within the context of that per-CPU kthread.
In such cases, the per-CPU kthread is already running, so attempting
to wake itself up does nothing except waste CPU cycles. This commit
therefore checks to see if it is in the per-CPU kthread context,
omitting the wakeup in this case.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree_plugin.h')
| -rw-r--r-- | kernel/rcutree_plugin.h | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 7b850cdc0aee..970329853dc5 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1291,11 +1291,9 @@ static void invoke_rcu_callbacks_kthread(void) local_irq_save(flags); __this_cpu_write(rcu_cpu_has_work, 1); - if (__this_cpu_read(rcu_cpu_kthread_task) == NULL) { - local_irq_restore(flags); - return; - } - wake_up_process(__this_cpu_read(rcu_cpu_kthread_task)); + if (__this_cpu_read(rcu_cpu_kthread_task) != NULL && + current != __this_cpu_read(rcu_cpu_kthread_task)) + wake_up_process(__this_cpu_read(rcu_cpu_kthread_task)); local_irq_restore(flags); } |