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-rw-r--r--kernel/rcutree.h19
-rw-r--r--kernel/rcutree_plugin.h42
-rw-r--r--kernel/rcutree_trace.c68
3 files changed, 125 insertions, 4 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 8db0cdc..d49046c 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -152,6 +152,25 @@ struct rcu_node {
wait_queue_head_t boost_wq;
/* Wait queue on which to park the boost */
/* kthread. */
+ unsigned long n_tasks_boosted;
+ /* Total number of tasks boosted. */
+ unsigned long n_exp_boosts;
+ /* Number of tasks boosted for expedited GP. */
+ unsigned long n_normal_boosts;
+ /* Number of tasks boosted for normal GP. */
+ unsigned long n_balk_blkd_tasks;
+ /* Refused to boost: no blocked tasks. */
+ unsigned long n_balk_exp_gp_tasks;
+ /* Refused to boost: nothing blocking GP. */
+ unsigned long n_balk_boost_tasks;
+ /* Refused to boost: already boosting. */
+ unsigned long n_balk_notblocked;
+ /* Refused to boost: RCU RS CS still running. */
+ unsigned long n_balk_notyet;
+ /* Refused to boost: not yet time. */
+ unsigned long n_balk_nos;
+ /* Refused to boost: not sure why, though. */
+ /* This can happen due to race conditions. */
#endif /* #ifdef CONFIG_RCU_BOOST */
struct task_struct *node_kthread_task;
/* kthread that takes care of this rcu_node */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 4e48625..07d3464 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1073,6 +1073,33 @@ static void __init __rcu_init_preempt(void)
#include "rtmutex_common.h"
+#ifdef CONFIG_RCU_TRACE
+
+static void rcu_initiate_boost_trace(struct rcu_node *rnp)
+{
+ if (list_empty(&rnp->blkd_tasks))
+ rnp->n_balk_blkd_tasks++;
+ else if (rnp->exp_tasks == NULL && rnp->gp_tasks == NULL)
+ rnp->n_balk_exp_gp_tasks++;
+ else if (rnp->gp_tasks != NULL && rnp->boost_tasks != NULL)
+ rnp->n_balk_boost_tasks++;
+ else if (rnp->gp_tasks != NULL && rnp->qsmask != 0)
+ rnp->n_balk_notblocked++;
+ else if (rnp->gp_tasks != NULL &&
+ ULONG_CMP_GE(jiffies, rnp->boost_time))
+ rnp->n_balk_notyet++;
+ else
+ rnp->n_balk_nos++;
+}
+
+#else /* #ifdef CONFIG_RCU_TRACE */
+
+static void rcu_initiate_boost_trace(struct rcu_node *rnp)
+{
+}
+
+#endif /* #else #ifdef CONFIG_RCU_TRACE */
+
/*
* Carry out RCU priority boosting on the task indicated by ->exp_tasks
* or ->boost_tasks, advancing the pointer to the next task in the
@@ -1108,10 +1135,14 @@ static int rcu_boost(struct rcu_node *rnp)
* expedited grace period must boost all blocked tasks, including
* those blocking the pre-existing normal grace period.
*/
- if (rnp->exp_tasks != NULL)
+ if (rnp->exp_tasks != NULL) {
tb = rnp->exp_tasks;
- else
+ rnp->n_exp_boosts++;
+ } else {
tb = rnp->boost_tasks;
+ rnp->n_normal_boosts++;
+ }
+ rnp->n_tasks_boosted++;
/*
* We boost task t by manufacturing an rt_mutex that appears to
@@ -1197,8 +1228,10 @@ static void rcu_initiate_boost(struct rcu_node *rnp)
{
struct task_struct *t;
- if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL)
+ if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
+ rnp->n_balk_exp_gp_tasks++;
return;
+ }
if (rnp->exp_tasks != NULL ||
(rnp->gp_tasks != NULL &&
rnp->boost_tasks == NULL &&
@@ -1209,7 +1242,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp)
t = rnp->boost_kthread_task;
if (t != NULL)
wake_up_process(t);
- }
+ } else
+ rcu_initiate_boost_trace(rnp);
}
/*
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 1cedf94..ead5736 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -157,6 +157,71 @@ static const struct file_operations rcudata_csv_fops = {
.release = single_release,
};
+#ifdef CONFIG_RCU_BOOST
+
+static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
+{
+ seq_printf(m, "%d:%d tasks=%c%c%c%c ntb=%lu neb=%lu nnb=%lu "
+ "j=%04x bt=%04x\n",
+ rnp->grplo, rnp->grphi,
+ "T."[list_empty(&rnp->blkd_tasks)],
+ "N."[!rnp->gp_tasks],
+ "E."[!rnp->exp_tasks],
+ "B."[!rnp->boost_tasks],
+ rnp->n_tasks_boosted, rnp->n_exp_boosts,
+ rnp->n_normal_boosts,
+ (int)(jiffies & 0xffff),
+ (int)(rnp->boost_time & 0xffff));
+ seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
+ " balk",
+ rnp->n_balk_blkd_tasks,
+ rnp->n_balk_exp_gp_tasks,
+ rnp->n_balk_boost_tasks,
+ rnp->n_balk_notblocked,
+ rnp->n_balk_notyet,
+ rnp->n_balk_nos);
+}
+
+static int show_rcu_node_boost(struct seq_file *m, void *unused)
+{
+ struct rcu_node *rnp;
+
+ rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
+ print_one_rcu_node_boost(m, rnp);
+ return 0;
+}
+
+static int rcu_node_boost_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_rcu_node_boost, NULL);
+}
+
+static const struct file_operations rcu_node_boost_fops = {
+ .owner = THIS_MODULE,
+ .open = rcu_node_boost_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+/*
+ * Create the rcuboost debugfs entry. Standard error return.
+ */
+static int rcu_boost_trace_create_file(struct dentry *rcudir)
+{
+ return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
+ &rcu_node_boost_fops);
+}
+
+#else /* #ifdef CONFIG_RCU_BOOST */
+
+static int rcu_boost_trace_create_file(struct dentry *rcudir)
+{
+ return 0; /* There cannot be an error if we didn't create it! */
+}
+
+#endif /* #else #ifdef CONFIG_RCU_BOOST */
+
static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
{
unsigned long gpnum;
@@ -315,6 +380,9 @@ static int __init rcutree_trace_init(void)
if (!retval)
goto free_out;
+ if (rcu_boost_trace_create_file(rcudir))
+ goto free_out;
+
retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
if (!retval)
goto free_out;
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