linux-kernel - Re: [PATCH 3/3] NOMMU: Make the initial mmap allocation excess behaviour Kconfig configurable

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Date:	Wed, 06 May 2009 12:42:41 +0100
From:	David Howells <dhowells@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	dhowells@...hat.com, torvalds@...ux-foundation.org,
	npiggin@...e.de, gerg@...pgear.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] NOMMU: Make the initial mmap allocation excess behaviour Kconfig configurable

Andrew Morton <akpm@...ux-foundation.org> wrote:

> Nasty problem.

Yes.  That's part of the fun of the NOMMU world.  It has many of the same
problems as the MMU world - just more exaggerated.

> > -int sysctl_nr_trim_pages = 1; /* page trimming behaviour */
> > +int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
> >  int heap_stack_gap = 0;
> >  
> 
> But there's a risk of -ENOMEM regression on other system here?

There shouldn't be (assuming you mean with this patch), the default is the
same as the original value.

> It's unlikely to be a huge problem for real-world embedded developers,
> as long as they know about this change.  And because you set the
> Kconfig default to "no change" then I guess they'll be none the wiser.
> 
> I think that patches 2 and 3 (and #1 unless I reorder and redo things)
> are 2.6.30 material.  Agree?

Assuming you mean go in before 2.6.30 is cut, then yes.  If you want, I can
reorder the patches to put #1 last.

David
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