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Wed, 07 Jan 2026 23:37:17 -0800 (PST) Received: from google.com ([2a00:79e0:2031:6:7bef:7c13:79b4:e9de]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3c4893dsm68875995ad.28.2026.01.07.23.37.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jan 2026 23:37:16 -0800 (PST) Date: Thu, 8 Jan 2026 16:37:11 +0900 From: Sergey Senozhatsky To: Yosry Ahmed Cc: Sergey Senozhatsky , Herbert Xu , Andrew Morton , Nhat Pham , Minchan Kim , Johannes Weiner , Brian Geffon , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 2/2] zsmalloc: chain-length configuration should consider other metrics Message-ID: References: <5p4iyah6zlrnxpbsis32c4m5lrjj3pq7xwcugq35d2entwfai2@n2r6y3ga2ie5> <7q5gqpfshnc3lfhzxughpks3fc2knw2delpm5io2oe54monydl@5isuxnjputjr> <9b7d6e6292c64f21b8d09def1b6723f02faffe88@linux.dev> <53zplsrqc66z4ea64cosy53zvttuuhgxr2ik7uw6i2zgluegyz@d3ulgntwnyw4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: e7pbw8x7aapnkczexfufc1f5yakcjjdx X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 6A3071C0002 X-Rspam-User: X-HE-Tag: 1767857838-384840 X-HE-Meta: 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 BV7mzQjC JUMqOLUB1Y0U31nvhxSbYzW9K8BzMXlx5vGea9ZLGNxwFjRelbt3nPxSU3qXtMj/Zad+8tIziLch+Ke3H9WlaCUWX8nvmn3VOQj9wugl2r4mqVBaDZ84RyArPl2HdL5W+bFPozfusWeCvrngfa6nWbkNlrxNToaZRzuwhZI99BtiVX6Dg74s9I/EQxXNH+0mLKlHFL2GI0HEWjg/WF6G7aCNBMoui9RKFi8++qnKzo2n2j0MgMT7tX/6jb+eVoJ/STpEuksv0LjlE0O2bcs7CZQnh0yQeFn5083T+KnbcvSddCmu7dT54i1jJsTxzpghYek/IZHJJ7vHGm5Zpf65cYkdR0oesZ1vrFO0mZ4HunCyQNjU= 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: List-Subscribe: List-Unsubscribe: On (26/01/07 17:12), Yosry Ahmed wrote: > On Wed, Jan 07, 2026 at 02:43:42PM +0900, Sergey Senozhatsky wrote: > > On (26/01/07 05:39), Yosry Ahmed wrote: > > > > On Tue, Jan 06, 2026 at 04:24:45PM +0000, Yosry Ahmed wrote: > > [..] > > > > Adding native SG support to LZO simply means removing the memcpy that > > > > scomp would otherwise have to do. > > > > > > Yeah the effort to add native support to compressors can be done > > > separately. For zswap, I think the most common compressors are > > > actually zstd and LZ4. > > > > I think it's the same for chromeos: lz4 (primary) and zstd > > (secondary/recompression). zstd looks very complicated, > > not sure if we really want to diverge its codebase from > > the upstream (meta github repo). > > I think there's value in using SG lists even if we do not have support > for lz4 or zstd. We'll remove the memcpy() logic in zsmalloc and the > kmap handling memcpy() in zswap if we just pass SG lists from zsmalloc > to zswap/zram. Yeah I agree, I guess I can cook something up. For transition period we can have: - current "memcpy" API for zswap - SG-list API I can vmap either on the zram side or have new zsmalloc vmap API (alongside the memcpy and SG-list APIs). Once crypto API supports SG-list and algorithms tunables I can switch zram over from zcomp to crypto API and remove memcpy and vmap APIs from zsmalloc.