Re: [ANNOUNCE][RFC] plugsched-2.0 patches ...

[Con Kolivas <kernel@kolivas.org>]

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Marc E. Fiuczynski wrote:
> Paraphrasing Jens Axboe:
> 
>>I don't think you can compare [plugsched with the plugio framework].
>>Yes they are both schedulers, but that's about where the 'similarity'
>>stops. The CPU scheduler must be really fast, overhead must be kept
>>to a minimum. For a disk scheduler, we can affort to burn cpu cycles
>>to increase the io performance. The extra abstraction required to
>>fully modularize the cpu scheduler would come at a non-zero cost as
>>well, but I bet it would have a larger impact there. I doubt you
>>could measure the difference in the disk scheduler.
> 
> 
> Modularization usually is done through a level of indirection (function
> pointers).  I have a can of "indirection be gone" almost ready to spray over
> the plugsched framework that would reduce the overhead to zero at runtime.
> I'd be happy to finish that work if it makes it more palpable to integrate a
> plugsched framework into the kernel?

The indirection was a minor point. On modern cpus it was suggested by 
wli that this would not be a demonstrable hit in perormance. Having said 
that, I'm sure Peter would be happy for another developer. I know how 
tiring and lonely it can feel maintaining such a monster.

Cheers,
Con

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