Subject: Re: pmap l1pt allocation strategy
To: None <Richard.Earnshaw@arm.com>
From: Ignatios Souvatzis <email@example.com>
Date: 11/28/2002 14:46:44
Content-Type: text/plain; charset=us-ascii
On Thu, Nov 28, 2002 at 09:52:15AM +0000, Richard Earnshaw wrote:
> > I've increased PMAP_STATIC_L1S to 128 and still get one or three per ev=
> That's quite a lot of active processes (though not necessarily=20
> unreasonable). How much RAM do you have?
> > Wouldn't the wiser strategy be:
> > 1. try if we have a free one on the l1pt free list
> > 2. if this fails, try to allocate a new one
> > 3. if this still fails, go to the static list?
> > This way, we only go to the static list if memory is fragmented or if we
> > run out of memory...
> > Would this fail during bootstrap? As the machine in question is my prod=
> > server, I don't want to waste time trying stupid things...
> > The only alternative to make this pmap stable would be to use a VAX-like
> > 16kB VM pages with 4KB mmu pages strategy, which naturally ensures that=
> > never run out of aligned 16kB blocks.
> It might make things a little more stable, though it would probably only=
> delay the onset of resource starvation slightly; and it would mean that=
> normally the static pool of L1S will be dead memory -- which argues for i=
> being a *much* lower number.
I agree here.
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