linux-kernel - Re: [RFC PATCH 0/6] Add support for shared PTEs across processes

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Message-ID: <20220125185705.wf7p2l77vggipfry@box.shutemov.name>
Date:   Tue, 25 Jan 2022 21:57:05 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Khalid Aziz <khalid.aziz@...cle.com>, akpm@...ux-foundation.org,
        longpeng2@...wei.com, arnd@...db.de, dave.hansen@...ux.intel.com,
        david@...hat.com, rppt@...nel.org, surenb@...gle.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC PATCH 0/6] Add support for shared PTEs across processes

On Tue, Jan 25, 2022 at 02:09:47PM +0000, Matthew Wilcox wrote:
> > I think zero-API approach (plus madvise() hints to tweak it) is worth
> > considering.
> 
> I think the zero-API approach actually misses out on a lot of
> possibilities that the mshare() approach offers.  For example, mshare()
> allows you to mmap() many small files in the shared region -- you
> can't do that with zeroAPI.

Do you consider a use-case for many small files to be common? I would
think that the main consumer of the feature to be mmap of huge files.
And in this case zero enabling burden on userspace side sounds like a
sweet deal.

-- 
 Kirill A. Shutemov