Messages in this thread | | | Date | Sun, 13 Nov 2005 23:44:51 -0800 | From | Andrew Morton <> | Subject | Re: start_kernel / local_irq_enable() can be very slow |
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Pozsar Balazs <pozsy@uhulinux.hu> wrote: > > I've noticed that the local_irq_enable() call in > init/main.c::start_kernel() takes 0.3 .. 3.0 seconds on every boot. > (Measured using printk's around it.) > > I am wondering what happens during this call (which is effectively one > "sti"), why does it take so much time sometimes, and why does it vary so > much, why isn't it (more) deterministic.
Presumably as soon as it does the sti, the CPU takes one or more interrupts and runs off and does something.
I wonder what?
You could do something like:
int trace_irqs;
trace_irqs = 1; local_irq_enble(); trace_irqs = 0;
then, over in handle_IRQ_event():
if (trace_irqs) print_symbol("calling %s\n", (unsigned long)action->handler);
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