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[70.77.221.9]) by smtp.gmail.com with ESMTPSA id w188sm14566273pfd.32.2021.08.30.11.34.56 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Aug 2021 11:34:56 -0700 (PDT) From: Andreas Dilger Message-Id: <8FEED5A6-DABE-4F29-9C1F-95A1B2E20190@dilger.ca> Content-Type: multipart/signed; boundary="Apple-Mail=_CEB5A37B-2F31-4800-8BF9-FF29B194CBBA"; protocol="application/pgp-signature"; micalg=pgp-sha256 Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: Discontiguous folios/pagesets Date: Mon, 30 Aug 2021 12:35:05 -0600 In-Reply-To: <20210830182818.GA9892@magnolia> Cc: Matthew Wilcox , Johannes Weiner , "Darrick J. Wong" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org To: "Darrick J. Wong" References: <1FC3646C-259F-4AA4-B7E0-B13E19EDC595@dilger.ca> <20210830182818.GA9892@magnolia> X-Mailer: Apple Mail (2.3273) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=dilger-ca.20150623.gappssmtp.com header.s=20150623 header.b=Zll8QDHW; spf=pass (imf11.hostedemail.com: domain of adilger@dilger.ca designates 209.85.216.51 as permitted sender) smtp.mailfrom=adilger@dilger.ca; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B82A8F0000AE X-Stat-Signature: zb3smkreqirkpdkoriar6oxgcgax3ox5 X-HE-Tag: 1630348498-952400 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --Apple-Mail=_CEB5A37B-2F31-4800-8BF9-FF29B194CBBA Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii > On Aug 30, 2021, at 12:28 PM, Darrick J. Wong wrote: > > On Sat, Aug 28, 2021 at 01:27:29PM -0600, Andreas Dilger wrote: >> On Aug 28, 2021, at 1:04 PM, Matthew Wilcox wrote: >>> >>> The current folio work is focused on permitting the VM to use >>> physically contiguous chunks of memory. Both Darrick and Johannes >>> have pointed out the advantages of supporting logically-contiguous, >>> physically-discontiguous chunks of memory. Johannes wants to be able to >>> use order-0 allocations to allocate larger folios, getting the benefit >>> of managing the memory in larger chunks without requiring the memory >>> allocator to be able to find contiguous chunks. Darrick wants to support >>> non-power-of-two block sizes. >> >> What is the use case for non-power-of-two block sizes? The main question >> is whether that use case is important enough to add the complexity and >> overhead in order to support it? > > For copy-on-write to a XFS realtime volume where the allocation extent > size (we support bigalloc too! :P) is not a power of two (e.g. you set > up a 4 disk raid5 with 64k stripes, now the extent size is 192k). > > Granted, I don't think folios handling 192k chunks is absolutely > *required* for folios; the only hard requirement is that if any page in > a 192k extent becomes dirty, the rest have to get written out all the > same time, and the cow remap can only happen after the last page > finishes writeback. OK, they are still multiples of PAGE_SIZE. That wasn't clear, I thought these were byte-granular IOs or something... Cheers, Andreas --Apple-Mail=_CEB5A37B-2F31-4800-8BF9-FF29B194CBBA Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIzBAEBCAAdFiEEDb73u6ZejP5ZMprvcqXauRfMH+AFAmEtJNkACgkQcqXauRfM H+BMbg//WkPjoSqpO0uyJFtCnuPsruBwvQiUx/noIiD9R/7TPNFhjVPixtkm/LM9 yx09eEuDtlHFZs3j4ZCD/mBpyy8GR6nXi7pE7nXv6PgMMweEQ5vkyc+G5IwMLgyD GQoDKAt5GG4yVvcYsNbd6jn6AFhj0nIZKD//OQL7oCqoqd6i9n7/W+pRt8nvOY/N Lr6eOjRNwdg1jWCkr5FgO+F4zl1OG1NXZ5UCLOGNlT3KhQpVjfxyvsZCyhjQxpjx reNZX3g2H6/6WWnBV+FAwlqh9G5mt8Fyh4Oqvt3i3nmYhwfJCIeMxM2i5i2O8EJG 2Gy8vxRRxFaBi2Nwh8R7Ne2BEL3YGwRPQzkWmC9s1ju6QhNdYjK62ZIHT34veBRE 3ehtF/xA0UISzVBwEkbY6HOVdfTVfUBxzKJwFsoceeerc4EdIymfeesANm31uLT8 yKFng+ZKBDodH6YhvxODf+wARzDBkrfXP1jMCvdvcvvab/uCYFpV2zeKBbj4DiAm 9d2MKIhbqXQiXjieAiJaXbAdg3zat8ajF9yuE1GM6I2bfXvBAhxdMnTwNtBKeZml 5vRNMlDiYMht0rdQY/aHPnTll6L7kExd9R5PjeVg75x57D3mdsVl/9N3Y9VVUAEr 8xWBdJ4RAuF3BON4LApuIFLEicxejOJo+8zKgEZNJGoSpGgCD8Y= =dDZs -----END PGP SIGNATURE----- --Apple-Mail=_CEB5A37B-2F31-4800-8BF9-FF29B194CBBA--