Messages in this thread | | | Date | Fri, 6 Apr 2001 14:00:52 +0200 | From | Pavel Machek <> | Subject | Re: softirq buggy [Re: Serial port latency] |
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Hi!
> > > Ok, there are 2 bugs that are (afaics) impossible to fix without > > > checking for pending softirq's in cpu_idle(): > > > > > > a) > > > queue_task(my_task1, tq_immediate); > > > mark_bh(); > > > schedule(); > > > ;within schedule: do_softirq() > > > ;within my_task1: > > > mark_bh(); > > > ; bh returns, but do_softirq won't loop > > > ; do_softirq returns. > > > ; schedule() clears current->need_resched > > > ; idle thread scheduled. > > > --> idle can run although softirq's are pending > > > > Or anything else can run altrough softirqs are pending. If it is > > computation job, softinterrupts are delayed quiet a bit, right? > > > > So right fix seems to be "loop in do_softirq". > > > No, it's the wrong fix. > A network server under high load would loop forever within the softirq, > never returning to process level. > > do_softirq cannot loop, the right fix is "check often for pending > softirq's". > It's checked before a process returns to user space, it's checked when a > process schedules. What's missing is that the idle functions must check > for pending softirqs, too.
Ok. I was missing the fact it is checked on going userspace.
-- The best software in life is free (not shareware)! Pavel GCM d? s-: !g p?:+ au- a--@ w+ v- C++@ UL+++ L++ N++ E++ W--- M- Y- R+ - 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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