Messages in this thread | | | Date | Sun, 27 May 2001 21:55:28 +0200 | From | Andrea Arcangeli <> | Subject | Re: [patch] severe softirq handling performance bug, fix, 2.4.5 |
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On Sun, May 27, 2001 at 09:05:50PM +0200, Ingo Molnar wrote: > > On Sun, 27 May 2001, Andrea Arcangeli wrote: > > > I mean everything is fine until the same softirq is marked active > > again under do_softirq, in such case neither the do_softirq in do_IRQ > > will run it (because we are in the critical section and we hold the ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > per-cpu locks), nor we will run it again ourself from the underlying ^^^^^^^^^^^^^ > > do_softirq to avoid live locking into do_softirq. > > if you mean the stock kernel, this scenario you describe is not how it
Yes the stock kernel.
> behaves, because only IRQ contexts can mark a softirq active again. And > those IRQ contexts will run do_IRQ() naturally, so while *this* > do_softirq() invocation wont run those reactivated softirqs, the IRQ > context that just triggered the softirq will do so.
it won't because the underlying do_softirq did local_bh_disable() and the in_interrupt() check will cause the do_softirq from do_IRQ to return immediatly.
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