Messages in this thread | | | Date | Tue, 14 Mar 2000 00:13:48 +0100 | From | Jamie Lokier <> | Subject | Re: new IRQ scalability changes in 2.3.48 |
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Andrea Arcangeli wrote: > >Note: In many cases, spinlock_irqsave doesn't need to do the > >spinlock_depth thing on UP. [..] > > It doesn't need that in SMP either.
An interrupt on another process can wake up a task and set current->need_resched on this processor.
> >[..] However, not all cases: the code in the > >lock region might wake up another task. > > If you wakeup another task you don't risk to get rescheduled before you > drop the lock.
Waking up another task may set current->need_resched. But it can't actually reschedule until reaching the spin_unlock_irqsave. At that point or some low-latency time later, you need to reschedule to get low latency.
-- Jamie
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