Re: page fault scalability patch V16 [3/4]: Drop page_table_lock in handle_mm_fault

From: Nick Piggin <nickpiggin_at_yahoo.com.au>
Date: 2005-02-02 14:09:37
On Tue, 2005-02-01 at 18:49 -0800, Christoph Lameter wrote:
> On Wed, 2 Feb 2005, Nick Piggin wrote:
> 
> > Well yeah, but the interesting case is when that isn't a lock ;)
> >
> > I'm not saying what you've got is no good. I'm sure it would be fine
> > for testing. And if it happens that we can do the "page_count doesn't
> > mean anything after it has reached zero and been freed. Nor will it
> > necessarily be zero when a new page is allocated" thing without many
> > problems, then this may be a fine way to do it.
> >
> > I was just pointing out this could be a problem without putting a
> > lot of thought into it...
> 
> Surely we need to do this the right way. Do we really need to
> use page_cache_get()? Is anything relying on page_count == 2 of
> the old_page?
> 
> I mean we could just speculatively copy, risk copying crap and
> discard that later when we find that the pte has changed. This would
> simplify the function:
> 

I think this may be the better approach. Anyone else?


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Received on Tue Feb 1 22:35:27 2005

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