Re: [PATCH][plugsched 0/28] Pluggable cpu scheduler framework

[William Lee Irwin III]

At some point in the past, Con Kolivas wrote:
>> This code was designed to touch the least number of files, be completely
>> arch-independant, and allow extra schedulers to be coded in by only
>> touching Kconfig, scheduler.c and scheduler.h. It should incur no
>> overhead when run and will allow you to compile in only the scheduler(s)
>> you desire. This allows, for example, embedded hardware to have a tiny
>> new scheduler that takes up minimal code space.

On Mon, Nov 01, 2004 at 12:33:13AM +0100, Pavel Machek wrote:
> You are changing 
> some_functions()
> into
> something->function()
> no? I do not think that is 0 overhead...

It's nonzero, yes. However, it's rather small with modern branch
predictors; older microarchitectures handled this less well, which
is probably why you expect a measurable hit. It may still have
non-negligible performance effects on some legacy architectures,
but I would not let that hold up progress.


-- wli
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