Messages in this thread Patch in this message | | | Date | Tue, 30 Dec 2014 17:52:28 -0200 | From | Marcelo Tosatti <> | Subject | [PATCH -rt] timer: upper bound on loops of __run_timers processing |
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Commit "timers: do not raise softirq unconditionally", allows for timer wheel processing (__run_timers) to be delayed for long periods of time.
The effect is that
loops = jiffies - base->timer_jiffies
Can grow to very large values resulting in __run_timers taking hundreds of milliseconds to execute.
Fix by creating an upper bound on the number of loops to be processed. This allows a nohz=off kernel to achieve desired latencies.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/kernel/timer.c b/kernel/timer.c index f59e18c..c128416 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1488,6 +1488,12 @@ void run_local_timers(void) } #endif + if (time_after_eq(jiffies, base->timer_jiffies)) { + unsigned long jiffies_delta = jiffies - base->timer_jiffies; + if (jiffies_delta > TVR_SIZE) + raise_softirq(TIMER_SOFTIRQ); + } + if (!base->active_timers) goto out;
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