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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-11-17 21:08:07 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-02-17 16:03:33 -0800 |
| commit | f1f399d1281ea339a08469f7e58193624992f620 (patch) | |
| tree | 915284120382e3180c3e58ba157cf045998549d0 | |
| parent | ffa83fb565fbc397cbafb4b71fd1cce276d4c3b6 (diff) | |
| download | linux-stable-f1f399d1281ea339a08469f7e58193624992f620.tar.gz linux-stable-f1f399d1281ea339a08469f7e58193624992f620.tar.bz2 linux-stable-f1f399d1281ea339a08469f7e58193624992f620.zip | |
rcu: Optimize RCU_FAST_NO_HZ for RCU_NOCB_CPU_ALL
If CONFIG_RCU_NOCB_CPU_ALL=y, then no CPU will ever have RCU callbacks
because these callbacks will instead be handled by the rcuo kthreads.
However, the current version of RCU_FAST_NO_HZ nevertheless checks for RCU
callbacks. This commit therefore creates static inline implementations
of rcu_prepare_for_idle() and rcu_cleanup_after_idle() that are no-ops
when CONFIG_RCU_NOCB_CPU_ALL=y.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 820b06aefbee..41afc3fbfb6c 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1658,7 +1658,7 @@ extern int tick_nohz_active; * only if it has been awhile since the last time we did so. Afterwards, * if there are any callbacks ready for immediate invocation, return true. */ -static bool rcu_try_advance_all_cbs(void) +static bool __maybe_unused rcu_try_advance_all_cbs(void) { bool cbs_ready = false; struct rcu_data *rdp; @@ -1743,6 +1743,7 @@ int rcu_needs_cpu(int cpu, unsigned long *dj) */ static void rcu_prepare_for_idle(int cpu) { +#ifndef CONFIG_RCU_NOCB_CPU_ALL struct rcu_data *rdp; struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); struct rcu_node *rnp; @@ -1794,6 +1795,7 @@ static void rcu_prepare_for_idle(int cpu) rcu_accelerate_cbs(rsp, rnp, rdp); raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ } +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ } /* @@ -1803,11 +1805,12 @@ static void rcu_prepare_for_idle(int cpu) */ static void rcu_cleanup_after_idle(int cpu) { - +#ifndef CONFIG_RCU_NOCB_CPU_ALL if (rcu_is_nocb_cpu(cpu)) return; if (rcu_try_advance_all_cbs()) invoke_rcu_core(); +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ } /* |