[PATCH tip/core/rcu 13/22] rcu: Add rcu_barrier() statistics to debugfs tracing

Paul E. McKenney
2012-06-22T15:29:43Z

From: "Paul E. McKenney" <paul.mckenney@linaro.org>

This commit adds an rcubarrier file to RCU's debugfs statistical tracing
directory, providing diagnostic information on rcu_barrier().

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
---
kernel/rcutree_trace.c | 39 +++++++++++++++++++++++++++++++++++++++
1 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index a3556a2..057408b 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -46,6 +46,40 @@
#define RCU_TREE_NONCORE
#include "rcutree.h"

+static void print_rcubarrier(struct seq_file *m, struct rcu_state *rsp)
+{
+ seq_printf(m, "%c bcc: %d nbd: %lu\n",
+ rsp->rcu_barrier_in_progress ? 'B' : '.',
+ atomic_read(&rsp->barrier_cpu_count),
+ rsp->n_barrier_done);
+}
+
+static int show_rcubarrier(struct seq_file *m, void *unused)
+{
+#ifdef CONFIG_TREE_PREEMPT_RCU
+ seq_puts(m, "rcu_preempt: ");
+ print_rcubarrier(m, &rcu_preempt_state);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+ seq_puts(m, "rcu_sched: ");
+ print_rcubarrier(m, &rcu_sched_state);
+ seq_puts(m, "rcu_bh: ");
+ print_rcubarrier(m, &rcu_bh_state);
+ return 0;
+}
+
+static int rcubarrier_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_rcubarrier, NULL);
+}
+
+static const struct file_operations rcubarrier_fops = {
+ .owner = THIS_MODULE,
+ .open = rcubarrier_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
#ifdef CONFIG_RCU_BOOST

static char convert_kthread_status(unsigned int kthread_status)
@@ -453,6 +487,11 @@ static int __init rcutree_trace_init(void)
if (!rcudir)
goto free_out;

+ retval = debugfs_create_file("rcubarrier", 0444, rcudir,
+ NULL, &rcubarrier_fops);
+ if (!retval)
+ goto free_out;
+
retval = debugfs_create_file("rcudata", 0444, rcudir,
NULL, &rcudata_fops);
if (!retval)
--
1.7.8