Re: [patch-2.4.0-test8-pre6] misc fixes

From: Tigran Aivazian (
Date: Thu Sep 07 2000 - 11:32:59 EST

On Thu, 7 Sep 2000, Linus Torvalds wrote:

> On Thu, 7 Sep 2000, Tigran Aivazian wrote:
> >
> > k) all swapout functions in mm/vmscan.c can be optimized by removing 'mm'
> > argument. This part was reviewed by Rick van Riel and approved.
> But they then get "mm" themselves anyway.
> What's the point? With argument passing, on certain architectures it stays
> in registers. On other architectures it is in memory on the stack, but
> that's not slower than accessing it from memory off another pointer.
> Linus

Linus, I am sorry to say this (because I know you are busy) but it would
appear you didn't look at the patch (that part of it). The patch does the
right thing, I believe, but my description was too brief.

If you look at those functions you will see that they sometimes access
'mm' via argument and sometimes via vm_mm->mm - this is a complete mess so
my patch tidies it up a bit.

In other words, if that 'mm' is available via vm_mm->mm there is no point
in passing it on the stack. Or if we pass it on the stack, there is no
point accessing it via vm_mm->mm. See my point now?


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