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Subject: Re: [PATCH] I3 sched tweaks...
From: Robert Love <rml@tech9.net>
To: mingo@elte.hu
Cc: Rusty Russell <rusty@rustcorp.com.au>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@transmeta.com>
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Date: 16 Jan 2002 16:10:09 -0500
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On Wed, 2002-01-16 at 17:46, Ingo Molnar wrote:

> we pass pointers across functions regularly, even if the pointer could be
> calculated within the function. We do this in the timer code too. It's
> slightly cheaper to pass an already existing (calculated) 'current'
> pointer over to another function, instead of calculating it once more in
> that function. This will be especially true once we make 'current' a tiny
> bit more expensive (Alan's kernel stack coloring rewrite will do that i
> think, it will be one more instruction to get 'current'.)

Maybe we should benchmark it?  It is very easy to calculate current.

Certainly I see the benefit if we start coloring the pointer (it adds 2
instructions I believe) but let's make sure it is worth passing another
32-bit argument.  It could very well be, schedule_tick is called
enough...

> > Moreover, the function doesn't make *sense* if p != current...
> 
> yes - would it be perhaps cleaner then to name the variable 'this_task' or
> something like that?

Yes, good idea.

	Robert Love

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