Re: [uml-devel] Re: [RFC] [patch 0/39] remap_file_pages protection support, try 2

[Blaisorblade]

On Sunday 14 August 2005 03:38, Ingo Molnar wrote:
> * Blaisorblade <blaisorblade@xxxxxxxx> wrote:

> > Ok, I've been working for the past two weeks learning well the Linux
> > VM, understanding the Ingo's remap_file_pages protection support and
> > its various weakness (due to lack of time on his part), and splitting
> > and finishing it.

> > Here follow a series of 39 _little_ patches against the git-commit-id
> > 889371f61fd5bb914d0331268f12432590cf7e85, which means between
> > 2.6.13-rc4 and -rc5.

> > Actually, the first 7 ones are unrelated trivial cleanups which
> > somehow get in the way on this work and that can probably be merged
> > even now (many are just comment fixes).

> > Since I was a VM newbie until two weeks ago, I've separated my changes
> > into many little patches.

> hi. Great work! I'm wondering about this comment in
Thanks for your appreciation.
> rfp-fix-unmap-linear.patch:
> > Additionally, add a missing TLB flush in both locations. However,
> > there'is some excess of flushes in these functions.

> excess TLB flushes one of the reasons of bad UML performance, so you
> should really review them and not do spurious TLB flushes.

After a bit of thought I realized that there was no spurious flush in those 
function, and that I didn't need to add any, because after setting a PTE as 
missing and flushing the TLB, I can freely alter it if I don't make it 
present again (right?), without other TLB flushes.
-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

		
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