Messages in this thread Patch in this message | | | Date | Thu, 29 Jun 2006 11:14:36 +0100 | From | Emmanuel Ackaouy <> | Subject | [PATCH] no_idle_hz (s390/xen) 2.6.16.13: fix next_timer_interrupt() when timer pending |
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Fix next_timer_interrupt() to return the expired timeout of any pending timer instead of the default "nothing scheduled" timeout value of jiffies+MAX_JIFFY_OFFSET. See comment in patch for details.
Signed-off-by: Emmanuel Ackaouy <ack@xensource.com>
diff -pruN pristine-linux-2.6.16.13/kernel/timer.c linux-2.6.16.13-xen/kernel/timer.c --- pristine-linux-2.6.16.13/kernel/timer.c 2006-05-02 22:38:44.000000000 +0100 +++ linux-2.6.16.13-xen/kernel/timer.c 2006-06-28 21:38:58.000000000 +0100 @@ -555,7 +555,17 @@ found: } spin_unlock(&base->t_base.lock); - if (time_before(hr_expires, expires)) + /* + * If timers are pending, "expires" will be in the recent past + * of "jiffies". If there are no hr_timers registered, "hr_expires" + * will be "jiffies + MAX_JIFFY_OFFSET"; this is *just* short of being + * considered to be before "jiffies". This makes it very likely that + * "hr_expires" *will* be considered to be before "expires". + * So we must check when there are pending timers (expires <= jiffies) + * to ensure that we don't accidently tell the caller that there is + * nothing scheduled until half an epoch (MAX_JIFFY_OFFSET)! + */ + if (time_before(jiffies, expires) && time_before(hr_expires, expires)) return hr_expires; return expires; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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