Re: [PATCH 1/3] Separate IRQ-stacks from 4K-stacks option

[Timothy Miller]

Lee Revell wrote:
> On Wed, 2004-10-20 at 11:35, Arjan van de Ven wrote:
>
> > On Wed, Oct 20, 2004 at 11:46:32AM -0400, Timothy Miller wrote:
> >
> > > The rules about how long a hard irq would be allowed to run would have 
> > > to be draconian.
> >
> > they already are.
>
>
> The IDE I/O completion in hardirq context means that one can run for
> almost 3ms.  Apparently at OLS it was decided that the target for
> desktop responsiveness was 1ms.  So this is a real problem.

What is happening that takes 3ms, and why can't it be broken up?

Are you talking here about PIO?  Is there a limited amount of time you 
have to do the PIO before the data goes away?  It may be acceptable to 
just live with PIO being slow, since high-performance systems will all 
be using DMA anyhow.

> What exactly do you mean by "draconian"?

In this case, I mean extremely harsh and restrictive.  Usually, it means 
"excessively harsh", but in this case, I mean that in a good way.  :)

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