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nohz: Track last do_timer() cpu

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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>
This commit is contained in:
Thomas Gleixner
2009-11-12 22:12:06 +01:00
parent 98962465ed
commit 27185016b8
2 changed files with 30 additions and 24 deletions
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2
include/linux/tick.h
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@ -43,6 +43,7 @@ enum tick_nohz_mode {
* @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 @@ struct tick_sched {
unsigned long last_jiffies;
unsigned long next_jiffies;
ktime_t idle_expires;
int do_timer_last;
};
extern void __init tick_init(void);