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[203.219.56.12]) by smtp.gmail.com with ESMTPSA id x189sm421549pfx.30.2021.09.03.16.42.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Sep 2021 16:42:06 -0700 (PDT) Date: Sat, 04 Sep 2021 09:42:00 +1000 From: Nicholas Piggin Subject: Re: Is it possible to implement the per-node page cache for programs/libraries? To: Matthew Wilcox Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Shijie Huang , song.bao.hua@hisilicon.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, Frank Wang References: <1630552995.2mupnzoqzs.astroid@bobo.none> <1630652670.aplcvu6g23.astroid@bobo.none> In-Reply-To: MIME-Version: 1.0 Message-Id: <1630712371.zxj5zdhheu.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Excerpts from Matthew Wilcox's message of September 4, 2021 5:01 am: > On Fri, Sep 03, 2021 at 05:10:31PM +1000, Nicholas Piggin wrote: >> Excerpts from Matthew Wilcox's message of September 2, 2021 8:17 pm: >> > On Thu, Sep 02, 2021 at 01:25:36PM +1000, Nicholas Piggin wrote: >> >> > I have been thinking about this a bit; one of our internal performa= nce >> >> > teams flagged the potential performance win to me a few months ago. >> >> > I don't have a concrete design for text replication yet; there have= been >> >> > various attempts over the years, but none were particularly compell= ing. >> >>=20 >> >> What was not compelling about it? >> >=20 >> > It wasn't merged, so clearly it wasn't compelling enough? >>=20 >> Ha ha. It sounded like you had some reasons you didn't find it=20 >> particularly compelling :P >=20 > I haven't studied it in detail, but it seems to me that your patch (from > 2007!) chooses whether to store pages or pcache_desc pointers in i_pages. > Was there a reason you chose to do it that way instead of having per-node > i_mapping pointers? What Linus said. The patch was obviously mechanism only and more=20 heuristics would need to be done (in that case you could have per inode=20 hints or whatever). > (And which way would you choose to do it now, given > the infrastructure we have now?) I'm not aware of anything new that would change it fundamentally. Thanks, Nick