rcu: Add tracing for synchronize_sched_expedited()

This commit adds a per-RCU-flavor "rcuexp" file that dumps out
statistics for synchonize_sched_expedited().

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 967115c508bc..f9512687a6e5 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -173,6 +173,38 @@ static const struct file_operations rcudata_fops = {
         .release = seq_release,
 };
 
+static int show_rcuexp(struct seq_file *m, void *v)
+{
+        struct rcu_state *rsp = (struct rcu_state *)m->private;
+
+        seq_printf(m, "s=%lu d=%lu w=%lu tf=%lu wd1=%lu wd2=%lu n=%lu sc=%lu dt=%lu dl=%lu dx=%lu\n",
+                   atomic_long_read(&rsp->expedited_start),
+                   atomic_long_read(&rsp->expedited_done),
+                   atomic_long_read(&rsp->expedited_wrap),
+                   atomic_long_read(&rsp->expedited_tryfail),
+                   atomic_long_read(&rsp->expedited_workdone1),
+                   atomic_long_read(&rsp->expedited_workdone2),
+                   atomic_long_read(&rsp->expedited_normal),
+                   atomic_long_read(&rsp->expedited_stoppedcpus),
+                   atomic_long_read(&rsp->expedited_done_tries),
+                   atomic_long_read(&rsp->expedited_done_lost),
+                   atomic_long_read(&rsp->expedited_done_exit));
+        return 0;
+}
+
+static int rcuexp_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, show_rcuexp, inode->i_private);
+}
+
+static const struct file_operations rcuexp_fops = {
+        .owner = THIS_MODULE,
+        .open = rcuexp_open,
+        .read = seq_read,
+        .llseek = no_llseek,
+        .release = seq_release,
+};
+
 #ifdef CONFIG_RCU_BOOST
 
 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
@@ -405,6 +437,11 @@ static int __init rcutree_trace_init(void)
                 if (!retval)
                         goto free_out;
 
+                retval = debugfs_create_file("rcuexp", 0444,
+                                rspdir, rsp, &rcuexp_fops);
+                if (!retval)
+                        goto free_out;
+
                 retval = debugfs_create_file("rcu_pending", 0444,
                                 rspdir, rsp, &rcu_pending_fops);
                 if (!retval)