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Subject[PATCH tip/core/rcu 05/14] rcu: Optimize the 'rcu_pending' for RCU trace
Date
From: Michael Wang <wangyun@linux.vnet.ibm.com>

This patch implements the new 'rcu_pending' interface under each rsp
directory, by using the 'CPU units sequence reading', thus avoiding loss
of tracing data.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree_trace.c | 41 +++++++++++++++++++++++++++++++++++------
1 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index e387a64..8b24867 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -467,6 +467,8 @@ static const struct file_operations rcugp_fops = {

static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
{
+ if (!rdp->beenonline)
+ return;
seq_printf(m, "%3d%cnp=%ld ",
rdp->cpu,
cpu_is_offline(rdp->cpu) ? '!' : ' ',
@@ -485,16 +487,12 @@ static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
static int show_rcu_pending(struct seq_file *m, void *unused)
{
int cpu;
- struct rcu_data *rdp;
struct rcu_state *rsp;

for_each_rcu_flavor(rsp) {
seq_printf(m, "%s:\n", rsp->name);
- for_each_possible_cpu(cpu) {
- rdp = per_cpu_ptr(rsp->rda, cpu);
- if (rdp->beenonline)
- print_one_rcu_pending(m, rdp);
- }
+ for_each_possible_cpu(cpu)
+ print_one_rcu_pending(m, per_cpu_ptr(rsp->rda, cpu));
}
return 0;
}
@@ -512,6 +510,32 @@ static const struct file_operations rcu_pending_fops = {
.release = single_release,
};

+static int new_show_rcu_pending(struct seq_file *m, void *v)
+{
+ print_one_rcu_pending(m, (struct rcu_data *)v);
+ return 0;
+}
+
+static const struct seq_operations new_rcu_pending_op = {
+ .start = r_start,
+ .next = r_next,
+ .stop = r_stop,
+ .show = new_show_rcu_pending,
+};
+
+static int new_rcu_pending_open(struct inode *inode, struct file *file)
+{
+ return r_open(inode, file, &new_rcu_pending_op);
+}
+
+static const struct file_operations new_rcu_pending_fops = {
+ .owner = THIS_MODULE,
+ .open = new_rcu_pending_open,
+ .read = seq_read,
+ .llseek = no_llseek,
+ .release = seq_release,
+};
+
static int show_rcutorture(struct seq_file *m, void *unused)
{
seq_printf(m, "rcutorture test sequence: %lu %s\n",
@@ -561,6 +585,11 @@ static int __init rcutree_trace_init(void)
rspdir, rsp, &new_rcudata_csv_fops);
if (!retval)
goto free_out;
+
+ retval = debugfs_create_file("rcu_pending", 0444,
+ rspdir, rsp, &new_rcu_pending_fops);
+ if (!retval)
+ goto free_out;
}

retval = debugfs_create_file("rcubarrier", 0444, rcudir,
--
1.7.8


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