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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-12-07 16:32:40 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-12-11 10:32:22 -0800
commit4968c300e1fa5389fdf1f1ebd8b8e4aec9aa4a9e (patch)
tree3424a8c3d2543096acad7319ec57fa8f62813620 /kernel
parent101db7b41d8d6c070278bca1f7bce814ecbf781d (diff)
downloadlinux-4968c300e1fa5389fdf1f1ebd8b8e4aec9aa4a9e.tar.bz2
rcu: Augment rcu_batch_end tracing for idle and callback state
The current rcu_batch_end event trace records only the name of the RCU flavor and the total number of callbacks that remain queued on the current CPU. This is insufficient for testing and tuning the new dyntick-idle RCU_FAST_NO_HZ code, so this commit adds idle state along with whether or not any of the callbacks that were ready to invoke at the beginning of rcu_do_batch() are still queued. 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')
-rw-r--r--kernel/rcutiny.c10
-rw-r--r--kernel/rcutiny_plugin.h25
-rw-r--r--kernel/rcutree.c8
3 files changed, 39 insertions, 4 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index e5bd94954fa3..977296dca0a4 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -259,7 +259,11 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
/* If no RCU callbacks ready to invoke, just return. */
if (&rcp->rcucblist == rcp->donetail) {
RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1));
- RCU_TRACE(trace_rcu_batch_end(rcp->name, 0));
+ RCU_TRACE(trace_rcu_batch_end(rcp->name, 0,
+ ACCESS_ONCE(rcp->rcucblist),
+ need_resched(),
+ is_idle_task(current),
+ rcu_is_callbacks_kthread()));
return;
}
@@ -288,7 +292,9 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
RCU_TRACE(cb_count++);
}
RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count));
- RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count));
+ RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count, 0, need_resched(),
+ is_idle_task(current),
+ rcu_is_callbacks_kthread()));
}
static void rcu_process_callbacks(struct softirq_action *unused)
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index 2b0484a5dc28..dfa97cbb3910 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -885,6 +885,19 @@ static void invoke_rcu_callbacks(void)
wake_up(&rcu_kthread_wq);
}
+#ifdef CONFIG_RCU_TRACE
+
+/*
+ * Is the current CPU running the RCU-callbacks kthread?
+ * Caller must have preemption disabled.
+ */
+static bool rcu_is_callbacks_kthread(void)
+{
+ return rcu_kthread_task == current;
+}
+
+#endif /* #ifdef CONFIG_RCU_TRACE */
+
/*
* This kthread invokes RCU callbacks whose grace periods have
* elapsed. It is awakened as needed, and takes the place of the
@@ -938,6 +951,18 @@ void invoke_rcu_callbacks(void)
raise_softirq(RCU_SOFTIRQ);
}
+#ifdef CONFIG_RCU_TRACE
+
+/*
+ * There is no callback kthread, so this thread is never it.
+ */
+static bool rcu_is_callbacks_kthread(void)
+{
+ return false;
+}
+
+#endif /* #ifdef CONFIG_RCU_TRACE */
+
void rcu_init(void)
{
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 2b2e1a996a65..6c4a6722abfd 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1373,7 +1373,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
/* If no callbacks are ready, just return.*/
if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
trace_rcu_batch_start(rsp->name, 0, 0);
- trace_rcu_batch_end(rsp->name, 0);
+ trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist),
+ need_resched(), is_idle_task(current),
+ rcu_is_callbacks_kthread());
return;
}
@@ -1409,7 +1411,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
}
local_irq_save(flags);
- trace_rcu_batch_end(rsp->name, count);
+ trace_rcu_batch_end(rsp->name, count, !!list, need_resched(),
+ is_idle_task(current),
+ rcu_is_callbacks_kthread());
/* Update count, and requeue any remaining callbacks. */
rdp->qlen -= count;