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| author | Ingo Molnar <mingo@kernel.org> | 2012-06-11 10:30:23 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-06-11 10:30:23 +0200 |
| commit | 4a1e001d2bb75c47a9cdbbfb66ae51daff1ddcba (patch) | |
| tree | 6d6e968a087b7a26b3a04af1ef94149607b64358 /kernel/time | |
| parent | memblock: Document memblock_is_region_{memory,reserved}() (diff) | |
| parent | rcu: Precompute RCU_FAST_NO_HZ timer offsets (diff) | |
| download | linux-4a1e001d2bb75c47a9cdbbfb66ae51daff1ddcba.tar.xz linux-4a1e001d2bb75c47a9cdbbfb66ae51daff1ddcba.zip | |
Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent
Merge RCU fixes from Paul E. McKenney:
" This series has four patches, the major point of which is to eliminate
some slowdowns (including boot-time slowdowns) resulting from some
RCU_FAST_NO_HZ changes. The issue with the changes is that posting timers
from the idle loop has no effect if the CPU has entered dyntick-idle
mode because the CPU has already computed its wakeup time, and posting
a timer does not cause it to be recomputed. The short-term fix is for
RCU to precompute the timeout value so that the CPU's calculation is
correct. "
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/tick-sched.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index da70c6db496c..869997833928 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -274,6 +274,7 @@ EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); static void tick_nohz_stop_sched_tick(struct tick_sched *ts) { unsigned long seq, last_jiffies, next_jiffies, delta_jiffies; + unsigned long rcu_delta_jiffies; ktime_t last_update, expires, now; struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; u64 time_delta; @@ -322,7 +323,7 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts) time_delta = timekeeping_max_deferment(); } while (read_seqretry(&xtime_lock, seq)); - if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) || + if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) || arch_needs_cpu(cpu)) { next_jiffies = last_jiffies + 1; delta_jiffies = 1; @@ -330,6 +331,10 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts) /* Get the next timer wheel timer */ next_jiffies = get_next_timer_interrupt(last_jiffies); delta_jiffies = next_jiffies - last_jiffies; + if (rcu_delta_jiffies < delta_jiffies) { + next_jiffies = last_jiffies + rcu_delta_jiffies; + delta_jiffies = rcu_delta_jiffies; + } } /* * Do not stop the tick, if we are only one off |