Re: [QUICKLIST 0/4] Arch independent quicklists V2

[Nick Piggin]

Andrew Morton wrote:
> > On Tue, 13 Mar 2007 23:01:11 +1100 Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
> > Andrew Morton wrote:

> > > It would be interesting to look at a) leave the page full of random garbage
> > > if we're releasing the whole mm and b) return it straight to the page allocator.
> >
> > Well we have the 'fullmm' case, which avoids all the locked pte operations
> > (for those architectures where hardware pt walking requires atomicity).
>
>
> I suspect there are some tlb operations which could be skipped in that case
> too.

Depends on the tlb flush implementation. The generic one doesn't look like
it is all that smart about optimising the fullmm case. It does skip some
tlb flushing though.

> > However we still have to visit those to-be-unmapped parts of the page table
> > to find the pages and free them. So we still at least need to bring it into
> > cache for the read... at which point, the store probably isn't a big burden.
>
>
> It means all that data has to be written back.  Yes, I expect it'll prove
> to be less costly than the initial load.

Still, it is something we could try.

--
SUSE Labs, Novell Inc.
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