nohz: Track last do_timer() cpu
The previous patch which limits the sleep time to the maximum
deferment time of the time keeping clocksource has some limitations on
SMP machines: if all CPUs are idle then for all CPUs the maximum sleep
time is limited.
Solve this by keeping track of which cpu had the do_timer() duty
assigned last and limit the sleep time only for this cpu.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Cc: Jon Hunter <jon-hunter@ti.com>
Cc: John Stultz <johnstul@us.ibm.com>
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 8dc0821..d2ae79e 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -43,6 +43,7 @@
* @idle_exittime: Time when the idle state was left
* @idle_sleeptime: Sum of the time slept in idle with sched tick stopped
* @sleep_length: Duration of the current idle sleep
+ * @do_timer_lst: CPU was the last one doing do_timer before going idle
*/
struct tick_sched {
struct hrtimer sched_timer;
@@ -64,6 +65,7 @@
unsigned long last_jiffies;
unsigned long next_jiffies;
ktime_t idle_expires;
+ int do_timer_last;
};
extern void __init tick_init(void);