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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-02-26 16:38:58 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-02-27 09:53:53 +0100 |
| commit | 71da81324c83ef65bb196c7f874ac1c6996d8287 (patch) | |
| tree | b470c5769ad88d2e2af8fe25cc84e7df85fb3d7c /kernel | |
| parent | 0b1c87278a8c7e394022ec184a0b44a3886b6fde (diff) | |
| download | op-kernel-dev-71da81324c83ef65bb196c7f874ac1c6996d8287.zip op-kernel-dev-71da81324c83ef65bb196c7f874ac1c6996d8287.tar.gz | |
rcu: Fix accelerated GPs for last non-dynticked CPU
This patch disables irqs across the call to rcu_needs_cpu(). It
also enforces a hold-off period so that the idle loop doesn't
softirq itself to death when there are lots of RCU callbacks in
flight on the last non-dynticked CPU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267231138-27856-3-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutree_plugin.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index ed241fc..464ad2c 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -986,6 +986,7 @@ static void rcu_needs_cpu_flush(void) #define RCU_NEEDS_CPU_FLUSHES 5 static DEFINE_PER_CPU(int, rcu_dyntick_drain); +static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff); /* * Check to see if any future RCU-related work will need to be done @@ -1013,6 +1014,7 @@ int rcu_needs_cpu(int cpu) for_each_cpu_not(thatcpu, nohz_cpu_mask) if (thatcpu != cpu) { per_cpu(rcu_dyntick_drain, cpu) = 0; + per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1; return rcu_needs_cpu_quick_check(cpu); } @@ -1022,6 +1024,7 @@ int rcu_needs_cpu(int cpu) per_cpu(rcu_dyntick_drain, cpu) = RCU_NEEDS_CPU_FLUSHES; } else if (--per_cpu(rcu_dyntick_drain, cpu) <= 0) { /* We have hit the limit, so time to give up. */ + per_cpu(rcu_dyntick_holdoff, cpu) = jiffies; return rcu_needs_cpu_quick_check(cpu); } @@ -1038,8 +1041,10 @@ int rcu_needs_cpu(int cpu) } /* If RCU callbacks are still pending, RCU still needs this CPU. */ - if (c) + if (c) { raise_softirq(RCU_SOFTIRQ); + per_cpu(rcu_dyntick_holdoff, cpu) = jiffies; + } return c; } @@ -1050,10 +1055,13 @@ int rcu_needs_cpu(int cpu) static void rcu_needs_cpu_flush(void) { int cpu = smp_processor_id(); + unsigned long flags; if (per_cpu(rcu_dyntick_drain, cpu) <= 0) return; + local_irq_save(flags); (void)rcu_needs_cpu(cpu); + local_irq_restore(flags); } #endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */ |
