From: Jason Gunthorpe <email@example.com> To: Joao Martins <firstname.lastname@example.org> Cc: "Dan Williams" <email@example.com>, "Matthew Wilcox" <firstname.lastname@example.org>, "Alex Sierra" <email@example.com>, "Andrew Morton" <firstname.lastname@example.org>, "Kuehling, Felix" <Felix.Kuehling@amd.com>, "Linux MM" <email@example.com>, "Ralph Campbell" <firstname.lastname@example.org>, linux-ext4 <email@example.com>, linux-xfs <firstname.lastname@example.org>, "amd-gfx list" <email@example.com>, "Maling list - DRI developers" <firstname.lastname@example.org>, "Christoph Hellwig" <email@example.com>, "Jérôme Glisse" <firstname.lastname@example.org>, "Alistair Popple" <email@example.com>, "Vishal Verma" <firstname.lastname@example.org>, "Dave Jiang" <email@example.com>, "Linux NVDIMM" <firstname.lastname@example.org>, "David Hildenbrand" <email@example.com> Subject: Re: [PATCH v1 2/2] mm: remove extra ZONE_DEVICE struct page refcount Date: Tue, 19 Oct 2021 13:01:36 -0300 [thread overview] Message-ID: <20211019160136.GH3686969@ziepe.ca> (raw) In-Reply-To: <firstname.lastname@example.org> On Tue, Oct 19, 2021 at 04:13:34PM +0100, Joao Martins wrote: > On 10/19/21 00:06, Jason Gunthorpe wrote: > > On Mon, Oct 18, 2021 at 12:37:30PM -0700, Dan Williams wrote: > > > >>> device-dax uses PUD, along with TTM, they are the only places. I'm not > >>> sure TTM is a real place though. > >> > >> I was setting device-dax aside because it can use Joao's changes to > >> get compound-page support. > > > > Ideally, but that ideas in that patch series have been floating around > > for a long time now.. > > > The current status of the series misses a Rb on patches 6,7,10,12-14. > Well, patch 8 too should now drop its tag, considering the latest > discussion. > > If it helps moving things forward I could split my series further into: > > 1) the compound page introduction (patches 1-7) of my aforementioned series > 2) vmemmap deduplication for memory gains (patches 9-14) > 3) gup improvements (patch 8 and gup-slow improvements) I would split it, yes.. I think we can see a general consensus that making compound_head/etc work consistently with how THP uses it will provide value and opportunity for optimization going forward. > Whats the benefit between preventing longterm at start > versus only after mounting the filesystem? Or is the intended future purpose > to pass more context into an holder potential future callback e.g. nack longterm > pins on a page basis? I understood Dan's remark that the device-dax path allows FOLL_LONGTERM and the FSDAX path does not ? Which, IIRC, today is signaled basd on vma properties and in all cases fast-gup is denied. > Maybe we can start by at least not add any flags and just prevent > FOLL_LONGTERM on fsdax -- which I guess was the original purpose of > commit 7af75561e171 ("mm/gup: add FOLL_LONGTERM capability to GUP fast"). > This patch (which I can formally send) has a sketch of that (below scissors mark): > > https://email@example.com/ Yes, basically, whatever test we want for 'deny fast gup foll longterm' is fine. Personally I'd like to see us move toward a set of flag specifying each special behavior and not a collection of types that imply special behaviors. Eg we have at least: - Block gup fast on foll_longterm - Capture the refcount ==1 and use the pgmap free hook (confusingly called page_is_devmap_managed()) - Always use a swap entry - page->index/mapping are used in the usual file based way? Probably more things.. Jason
next prev parent reply other threads:[~2021-10-19 16:01 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-14 15:39 [PATCH v1 0/2] " Alex Sierra 2021-10-14 15:39 ` [PATCH v1 1/2] ext4/xfs: add page refcount helper Alex Sierra 2021-10-14 16:25 ` Jason Gunthorpe 2021-10-14 16:40 ` Matthew Wilcox 2021-10-14 15:39 ` [PATCH v1 2/2] mm: remove extra ZONE_DEVICE struct page refcount Alex Sierra 2021-10-14 16:52 ` Matthew Wilcox 2021-10-14 17:06 ` Jason Gunthorpe 2021-10-14 17:35 ` Ralph Campbell 2021-10-14 18:01 ` Jason Gunthorpe 2021-10-14 20:57 ` Ralph Campbell 2021-10-15 3:45 ` Sierra Guiza, Alejandro (Alex) 2021-10-15 11:06 ` Jason Gunthorpe 2021-10-14 18:43 ` Matthew Wilcox 2021-10-14 19:01 ` Dan Williams 2021-10-14 23:06 ` Jason Gunthorpe 2021-10-15 1:37 ` Dan Williams 2021-10-16 15:44 ` Jason Gunthorpe 2021-10-16 16:39 ` Matthew Wilcox 2021-10-17 18:20 ` Dan Williams 2021-10-17 18:35 ` Dan Williams 2021-10-18 18:25 ` Jason Gunthorpe 2021-10-18 19:37 ` Dan Williams 2021-10-18 23:06 ` Jason Gunthorpe 2021-10-19 15:13 ` Joao Martins 2021-10-19 16:01 ` Jason Gunthorpe [this message] 2021-10-19 19:21 ` Dan Williams 2021-10-20 17:06 ` Joao Martins 2021-10-20 17:12 ` Dan Williams 2021-10-20 18:51 ` Joao Martins 2021-11-15 19:33 [PATCH v1 0/2] Remove extra ZONE_DEVICE " Alex Sierra 2021-11-15 19:33 ` [PATCH v1 2/2] mm: remove extra ZONE_DEVICE struct " Alex Sierra
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20211019160136.GH3686969@ziepe.ca \ --firstname.lastname@example.org \ --cc=Felix.Kuehling@amd.com \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --subject='Re: [PATCH v1 2/2] mm: remove extra ZONE_DEVICE struct page refcount' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).