interrupt latency and driver locking
John Polstra
jdp at polstra.com
Sat Sep 20 13:00:58 PDT 2003
On 20-Sep-2003 Luigi Rizzo wrote:
> the main problem, as i see it, is that when there are PHY events you
> still need to do some expensive work while holding a lock that
> blocks interrupts, with very bad impact on the worst-case
> response of the system.
I agree that is a problem, but I don't think it is the main problem.
In a running system, PHY events essentially never happen, so it
doesn't matter much if they take a long time. In other words, the PHY
really only needs attention when the link state changes, and for all
practical purposes that never happens in a running system.
What is killing us is the periodic polling of the PHY every second,
only to find out that nothing has changed.
John
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