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

Nick Piggin
2005-02-02T03:09:37Z

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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