linux-kernel - [PATCH v2 6/8] sched: Intoduce get_cpu_iowait_time

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20100509082523.284feab6@infradead.org>
Date:	Sun, 9 May 2010 08:25:23 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, davej@...hat.com
Subject: [PATCH v2  6/8] sched: Intoduce get_cpu_iowait_time_us()

From: Arjan van de Ven <arjan@...ux.intel.com>

For the ondemand cpufreq governor, it is desired that the iowait
time is microaccounted in a similar way as idle time is.

This patch introduces the infrastructure to account and expose
this information via the get_cpu_iowait_time_us() function.

[akpm@...ux-foundation.org: fix CONFIG_NO_HZ=n build]
Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Rik van Riel <riel@...hat.com>
---

 include/linux/tick.h     |    4 ++++
 kernel/time/tick-sched.c |   28 ++++++++++++++++++++++++++++
 kernel/time/timer_list.c |    1 +
 3 files changed, 33 insertions(+)

diff -puN include/linux/tick.h~sched-introduce-get_cpu_iowait_time_us include/linux/tick.h
--- a/include/linux/tick.h~sched-introduce-get_cpu_iowait_time_us
+++ a/include/linux/tick.h
@@ -42,6 +42,7 @@ enum tick_nohz_mode {
  * @idle_waketime:	Time when the idle was interrupted
  * @idle_exittime:	Time when the idle state was left
  * @idle_sleeptime:	Sum of the time slept in idle with sched tick stopped
+ * @iowait_sleeptime:	Sum of the time slept in idle with sched tick stopped, with IO outstanding
  * @sleep_length:	Duration of the current idle sleep
  * @do_timer_lst:	CPU was the last one doing do_timer before going idle
  */
@@ -60,6 +61,7 @@ struct tick_sched {
 	ktime_t				idle_waketime;
 	ktime_t				idle_exittime;
 	ktime_t				idle_sleeptime;
+	ktime_t				iowait_sleeptime;
 	ktime_t				sleep_length;
 	unsigned long			last_jiffies;
 	unsigned long			next_jiffies;
@@ -123,6 +125,7 @@ extern void tick_nohz_stop_sched_tick(in
 extern void tick_nohz_restart_sched_tick(void);
 extern ktime_t tick_nohz_get_sleep_length(void);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
+extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
 # else
 static inline void tick_nohz_stop_sched_tick(int inidle) { }
 static inline void tick_nohz_restart_sched_tick(void) { }
@@ -133,6 +136,7 @@ static inline ktime_t tick_nohz_get_slee
 	return len;
 }
 static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
+static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
 # endif /* !NO_HZ */
 
 #endif
diff -puN kernel/time/tick-sched.c~sched-introduce-get_cpu_iowait_time_us kernel/time/tick-sched.c
--- a/kernel/time/tick-sched.c~sched-introduce-get_cpu_iowait_time_us
+++ a/kernel/time/tick-sched.c
@@ -161,6 +161,8 @@ update_ts_time_stats(struct tick_sched *
 	if (ts->idle_active) {
 		delta = ktime_sub(now, ts->idle_entrytime);
 		ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
+		if (nr_iowait_cpu() > 0)
+			ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
 		ts->idle_entrytime = now;
 	}
 
@@ -220,6 +222,32 @@ u64 get_cpu_idle_time_us(int cpu, u64 *l
 }
 EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
 
+/*
+ * get_cpu_iowait_time_us - get the total iowait time of a cpu
+ * @cpu: CPU number to query
+ * @last_update_time: variable to store update time in
+ *
+ * Return the cummulative iowait time (since boot) for a given
+ * CPU, in microseconds.
+ *
+ * This time is measured via accounting rather than sampling,
+ * and is as accurate as ktime_get() is.
+ *
+ * This function returns -1 if NOHZ is not enabled.
+ */
+u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+
+	if (!tick_nohz_enabled)
+		return -1;
+
+	update_ts_time_stats(ts, ktime_get(), last_update_time);
+
+	return ktime_to_us(ts->iowait_sleeptime);
+}
+EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
+
 /**
  * tick_nohz_stop_sched_tick - stop the idle tick from the idle task
  *
diff -puN kernel/time/timer_list.c~sched-introduce-get_cpu_iowait_time_us kernel/time/timer_list.c
--- a/kernel/time/timer_list.c~sched-introduce-get_cpu_iowait_time_us
+++ a/kernel/time/timer_list.c
@@ -176,6 +176,7 @@ static void print_cpu(struct seq_file *m
 		P_ns(idle_waketime);
 		P_ns(idle_exittime);
 		P_ns(idle_sleeptime);
+		P_ns(iowait_sleeptime);
 		P(last_jiffies);
 		P(next_jiffies);
 		P_ns(idle_expires);
_
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/