Re: serial driver irq takes too long (fwd)

[Russell King - ARM Linux Admin]

Godmar Back writes:
> here's a copy of a message I sent to the general linux kernel mailing list.
> As this happens with a StrongARM (though I don't believe it's StrongARM
> specific), maybe someone on this mailing list may have an insight as
> to why the serial driver runs with irqs off.

I don't think this is a serial-specific problem.  Sound IRQs should not
be high priority - serial should certainly override the sound IRQ at any
cost.

What does really impact the IRQ performance is the hard disk.  Here,
I can stop sound output dead, and even slow down the 100Hz timer due
to hard disk activity.  For instance, if I do a hdparm -t /dev/hda,
it could come out at 4MB/s.  I know for a fact that it's only doing
2MB/s though.  hdparm -u1 /dev/hda fixes this, and indeed, I run by
default all my drives with unmasking enabled.

I would suggest that you also try this to see if it fixes your problem.
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