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    SubjectRe: [patch] severe softirq handling performance bug, fix, 2.4.5

    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
    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.

    the real source of softirq latencies is the local_bh_disable()/enable()
    behavior, see my previous patch.


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