[PATCH v15 7/7] io-throttle: export per-task statistics to userspace

[Andrea Righi]

Export the throttling statistics collected for each task through
/proc/PID/io-throttle-stat.

Example:
  $ cat /proc/$$/io-throttle-stat
  0 0 0 0
  ^ ^ ^ ^
   \ \ \ \_____global iops sleep (in clock ticks)
    \ \ \______global iops counter
     \ \_______global bandwidth sleep (in clock ticks)
      \________global bandwidth counter

Signed-off-by: Andrea Righi <righi.andrea at gmail.com>
---
 fs/proc/base.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index aa763ab..94061bf 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -54,6 +54,7 @@
 #include <linux/proc_fs.h>
 #include <linux/stat.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
 #include <linux/init.h>
 #include <linux/capability.h>
 #include <linux/file.h>
@@ -2453,6 +2454,17 @@ static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)
 }
 #endif /* CONFIG_TASK_IO_ACCOUNTING */
 
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+static int proc_iothrottle_stat(struct task_struct *task, char *buffer)
+{
+	return sprintf(buffer, "%llu %llu %llu %llu\n",
+			get_io_throttle_cnt(task, IOTHROTTLE_BANDWIDTH),
+			get_io_throttle_sleep(task, IOTHROTTLE_BANDWIDTH),
+			get_io_throttle_cnt(task, IOTHROTTLE_IOPS),
+			get_io_throttle_sleep(task, IOTHROTTLE_IOPS));
+}
+#endif /* CONFIG_CGROUP_IO_THROTTLE */
+
 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
 				struct pid *pid, struct task_struct *task)
 {
@@ -2539,6 +2551,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	INF("io",	S_IRUGO, proc_tgid_io_accounting),
 #endif
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+	INF("io-throttle-stat",	S_IRUGO, proc_iothrottle_stat),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file * filp,
@@ -2874,6 +2889,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	INF("io",	S_IRUGO, proc_tid_io_accounting),
 #endif
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+	INF("io-throttle-stat",	S_IRUGO, proc_iothrottle_stat),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file * filp,
-- 
1.6.0.4