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[PATCH tip/core/rcu 04/23] rcu: ignore offline CPUs in last non-dyntick-idle CPU check

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From: Paul E. McKenney
Subject: [PATCH tip/core/rcu 04/23] rcu: ignore offline CPUs in last non-dyntick-idle CPU check
Date: Tuesday, April 20, 2010 - 2:44 pm

From: Lai Jiangshan <laijs@cn.fujitsu.com>

Offline CPUs are not in nohz_cpu_mask, but can be ignored when checking
for the last non-dyntick-idle CPU.  This patch therefore only checks
online CPUs for not being dyntick idle, allowing fast entry into
full-system dyntick-idle state even when there are some offline CPUs.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutree_plugin.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 79b53bd..687c4e9 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1016,7 +1016,7 @@ int rcu_needs_cpu(int cpu)
 
 	/* Don't bother unless we are the last non-dyntick-idle CPU. */
 	for_each_cpu_not(thatcpu, nohz_cpu_mask)
-		if (thatcpu != cpu) {
+		if (cpu_online(thatcpu) && thatcpu != cpu) {
 			per_cpu(rcu_dyntick_drain, cpu) = 0;
 			per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
 			return rcu_needs_cpu_quick_check(cpu);
-- 
1.7.0

--
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Messages in current thread:
[PATCH tip/core/rcu 0/23] v3 patches queued for 2.6.35, Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 01/23] rcu: substitute set_need_resche ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 02/23] rcu: make dead code really dead, Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 03/23] rcu: move some code from macro ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 04/23] rcu: ignore offline CPUs in las ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 05/23] rcu: Fix bogus CONFIG_PROVE_LOC ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 06/23] rcu: fix now-bogus rcu_schedule ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 07/23] rcu: shrink rcutiny by making s ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 08/23] rcu: rename rcutiny rcu_ctrlblk ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 09/23] rcu: refactor RCU's context-swi ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 10/23] rcu: slim down rcutiny by remov ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 11/23] rcu: enable CPU_STALL_VERBOSE b ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 12/23] rcu: disable CPU stall warnings ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 13/23] rcu: print boot-time console me ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 14/23] rcu: improve RCU CPU stall-warn ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 15/23] rcu: permit discontiguous cpu_p ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 16/23] rcu: v2: reduce the number of s ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 17/23] rcu: improve the RCU CPU-stall ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 18/23] Debugobjects transition check, Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 19/23] rcu head introduce rcu head ini ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 20/23] remove all rcu head initializat ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 21/23] rcu head remove init, Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 22/23] tree/tiny rcu: Add debug RCU he ..., Paul E. McKenney, (Tue Apr 20, 2:44 pm)
[PATCH tip/core/rcu 23/23] rcu: make SRCU usable in modules, Paul E. McKenney, (Tue Apr 20, 2:44 pm)