start_kernel / local_irq_enable() can be very slow

[Pozsar Balazs]

Hi all,

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.


This is a x86 machine, I can give more details if needed.
I've observed this behaviour on a few other machines too.


Anybody any clues?
thanks,

-- 
pozsy
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