[PATCH 3/3] xfree86: Add a conservative SIGIO handler path

[Adam Jackson]

On Thu, 2010-10-14 at 16:26 -0300, Tiago Vignatti wrote:
> On Thu, Oct 14, 2010 at 06:49:06PM +0200, ext Adam Jackson wrote:
> > Instead of actually processing input in the handler, the conservative
> > path just raises enough of a dispatch exception to bomb out of request
> > processing and handle input instead.
> 
> ajax, I understand the rationale but would be great if you elaborate a bit
> defending why we need _another_ method here. We're adding more complexity and,
> for instance, we would have to justify the removal of this new method when
> introducing the input-thread given I was already assuming like dead all SIGIO
> paths.
> 
> So, to better accomplish this all, we need to perform and benchmark:
> 1. input thread
> 2. aggressive SIGIO (current one by default on linux) 
> 3. conservative SIGIO (raising up isItTimeToYield)
> 4. old input processing using the main thread handler
> 
> Do you have some thoughts on those?

Actually, what I want to see is:

1: input threads if you have working threads
2: classic-ish input processing if you don't, with something like the
conservative SIGIO handler as a helper if your platform has SIGIO
support

Which should be a material improvement for everybody, even if it doesn't
reduce the number of code paths it's at least no more complex than what
we have.

- ajax
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