Re: softirq buggy [Re: Serial port latency]

[kuznet]

Hello!

> But with a huge overhead. I'd prefer to call it directly from within the
> idle functions, the overhead of schedule is IMHO too high.


+       if (current->need_resched) {
+               return 0;
                ^^^^^^^^
+       }
+       if (softirq_active(smp_processor_id()) & softirq_mask(smp_processor_id())) {
+               do_softirq();
+               return 0;
                ^^^^^^^^^
You return one value in both casesand I decided it means "schedule". 8)
Apparently you meaned return 1 in the first case. 8)

But in this case it becomes wrong. do_softirq() can raise need_reshed
and moreover irqs arrive during it. Order of check should be different.


BTW what's about overhead... I suspect it is _lower_ in the case
of schedule(). In the case of networking at least, when softirq
most likely wakes some socket.

Alexey
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