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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-04-06 16:01:16 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-05-05 23:16:56 -0700
commit15ba0ba860871cf74b48b1bb47c26c91a66126f3 (patch)
tree2043eeca7d6df62fc0ae918b61abada073f81415 /kernel/rcutree.c
parenta9f4793d8900dc5dc09b3951bdcd4731290e06fe (diff)
downloadlwn-15ba0ba860871cf74b48b1bb47c26c91a66126f3.tar.gz
lwn-15ba0ba860871cf74b48b1bb47c26c91a66126f3.zip
rcu: add grace-period age and more kthread state to tracing
This commit adds the age in jiffies of the current grace period along with the duration in jiffies of the longest grace period since boot to the rcu/rcugp debugfs file. It also adds an additional "O" state to kthread tracing to differentiate between the kthread waiting due to having nothing to do on the one hand and waiting due to being on the wrong CPU on the other hand. 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.c')
-rw-r--r--kernel/rcutree.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index bb84deca3319..27b6d8de82f6 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -92,6 +92,7 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);
*/
static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
+DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu);
static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq);
DEFINE_PER_CPU(char, rcu_cpu_has_work);
static char rcu_kthreads_spawnable;
@@ -888,6 +889,8 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
__releases(rcu_get_root(rsp)->lock)
{
+ unsigned long gp_duration;
+
WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
/*
@@ -895,6 +898,9 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
* is seen before the assignment to rsp->completed.
*/
smp_mb(); /* See above block comment. */
+ gp_duration = jiffies - rsp->gp_start;
+ if (gp_duration > rsp->gp_max)
+ rsp->gp_max = gp_duration;
rsp->completed = rsp->gpnum;
rsp->signaled = RCU_GP_IDLE;
rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
@@ -1583,12 +1589,15 @@ static int rcu_cpu_kthread_should_stop(int cpu)
smp_processor_id() != cpu) {
if (kthread_should_stop())
return 1;
+ per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
+ per_cpu(rcu_cpu_kthread_cpu, cpu) = raw_smp_processor_id();
local_bh_enable();
schedule_timeout_uninterruptible(1);
if (!cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)))
set_cpus_allowed_ptr(current, cpumask_of(cpu));
local_bh_disable();
}
+ per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
return 0;
}
@@ -1656,6 +1665,7 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu)
if (IS_ERR(t))
return PTR_ERR(t);
kthread_bind(t, cpu);
+ per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL);
per_cpu(rcu_cpu_kthread_task, cpu) = t;
wake_up_process(t);