[RFC][PATCH -mm 5/5] export per-task i/o throttling statistics to userspace

[Andrea Righi]

Export the throttling statistics collected for each task through
/proc/PID/io-throttle-stat:
 - total number of delayed I/O request
 - total amount of time in jiffies spent to wait for the delayed requests

Signed-off-by: Andrea Righi <righi.andrea at gmail.com>
---
 fs/proc/base.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 01ed610..9983730 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>
@@ -2440,6 +2441,14 @@ 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\n",
+		get_io_throttle_cnt(task), get_io_throttle_sleep(task));
+}
+#endif /* CONFIG_CGROUP_IO_THROTTLE */
+
 /*
  * Thread groups
  */
@@ -2515,6 +2524,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	INF("io",	S_IRUGO, tgid_io_accounting),
 #endif
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+	INF("io-throttle-stat",	S_IRUGO, iothrottle_stat),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file * filp,
@@ -2846,6 +2858,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	INF("io",	S_IRUGO, tid_io_accounting),
 #endif
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+	INF("io-throttle-stat",	S_IRUGO, iothrottle_stat),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file * filp,
-- 
1.5.4.3