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dmarc=pass (policy=none) header.from=sina.com; spf=pass (imf23.hostedemail.com: domain of hdanton@sina.com designates 61.135.153.165 as permitted sender) smtp.mailfrom=hdanton@sina.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1792569220; b=TKYqVfWptwxIqJhFaDdagKk9S9UITUKHyLi88MtbFW770QQEj6S7W6axg0L6X57CKwAnUL jmLcYlsgNWUeIWjfQN1k0twfkQpN8HHmQ7ob4GtOvQsu1Nu6mRuu5qfBDIH0kgWT17BGwJ dr1pjEIV/BM6Z77ZJcb5Nbx/g1nlCqs= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1792569218; bh=bhy0oyRetX168I3CYw/iHInrZZxLMV6KJR6cfcucIJA=; h=From:Subject:Date:Message-ID; b=aV8uqU9Ko0owg2WYvOD+Myng8ppxQGjd6SQrAE6PxAQHJ1ysStyFJgOnqWNB5i26H UqhmpSChGujNbw02V/3TmZR88vJUrDcAQZuiE3hajbbneS503/1fD1gTOwn645ejA3 bYt1rP2LOoJGdPYtymqQQ9ncXu2ZKcP2CvhBjCIQ= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.254.3.56]) by sina.com (10.54.253.32) with ESMTP id 6AD86F7A00002678; Wed, 21 Oct 2026 15:53:33 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 5760734456874 X-SMAIL-UIID: A986B4A8D67249C0A2750D2D5F8A8120-20261021-155333-1 From: Hillf Danton To: Sergey Senozhatsky Cc: Andrew Morton , Brian Geffon , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v6 09/13] zram: split zcomp into separate R/W streams Date: Wed, 21 Oct 2026 15:53:21 +0800 Message-ID: <20261021075322.923-1-hdanton@sina.com> In-Reply-To: References: X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: D1C40140005 X-Stat-Signature: cuf9sh13u44k76qkjre7w35nzypp65yp X-Spam-Status: No, score=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1792569217-818324 X-HE-Meta: U2FsdGVkX1+9QxdUYiLtXY14U7PLi52jH49FeA2wcOa7YNZhD9Y9/knQme5RYohxSbdOeThoquqv/HsjcF531+3srcH/KBEM1i5X5OuEec2S/eAo0WNQxvmy8BeezxJcWIfmurEIbvCvBbK9prA0iuGtOe4aqoN/9TCQZnhpzybSNSvckr0GKQBaLkbdSNzsGyNc6D30J/FTVVdf5r4OqHi1eXEAJk5jmlyDVKKyMgbopiJf5/46kHQHzuT/YsfeDDjdP+/o8hNA76glrbvDQasN/PwbPmg2LI73VsLAMA+f+6r1SHksle7HmZHuJm1VrDTPKBJJG+izFXGk9n/eLVedML2zwiAozE6OJTUeQ3dXpdHnbCfbPxtNhWs1YXUOUFkgAWeTCoxanPbQ835ufrkimhf0AgH5nCjoYwZHYGteneSF9lqzZCXWE5g+YwBLGIgBGVxwh1mADGTGKdLGfK/nPkeJBe4LMKM46eJ+parOX+QFGSSeXcW+vM+K1GcPS3TTsAEiUqC4cmq3xK1SchtbJQ40qlA11PDPDaEbD//dSlrPQBtBy38ZV3yQYrPhoGiuRpUtg8Akkz3oO+EuA7BUQPaKUhRgM9frR9h8jp+BFwq/IYwCZvyEm8n9+QzQS66KrohqUdYAkZ0r4pXdygzn7Qy4UC1Gr1Xene1MB6xqnL0hEgzvF8mmqWhR5zVcQHVChGcdRlw0BgaxRNCHqhq2asgKSW8sjUXqTr5ObnAnYzezrXYs/pZl3GQS+TH5oNI/ZYkD43FvcJT5HcwwgNh9dZ5+pexq3Hzs3l9QUak1tb+qXV3XfGINgcUM6uTS3+18jHj8FTRIyYewUN9lJ4AVAXwPOPcU2O57rpOpb+Z3LqH6dqTX1WQ/I4UkDdpuLO7HYTGYslzeABMCeYp+RqWFuvbTLLuWG42IDW2ZhtcDaeVWiGfhcE8BW6Gc2kfCpJBKBp6XZixm3VHqpUG XEy/Ide+ qS262PWU+qxZdTIct0cabKrsdWIpN1o2UO+cmpwe/37LjzLQU/NVESzc/MK4xK3kIfmnrZAp/Nwq7aYSHaMICx9zsJPOB03CH9mtElTXjeYZVBhHcWFToNWGI8m75sp2UFDyjyJS28k6pbQ2RZ9kpk50aDZvp3a/5Bm8wcjVpXJ023X5fYflezT7NIdsZMGIz5gwVAqtxGYrGJiM9ZNA8qrdbHazbWaBh/wKiqxKT4Dkve5bFQBV0zd5CLc3ZrpoAgFP/Hd70s1QchQYrlh1mfeHgcT8BbZLzLC+VNH0ry4qXTl7mgOK8ytEfLsiB+TstxrxkOnod9XFVzAVFgOEPkN97zIPRid9nL5zj Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, 21 Oct 2026 13:56:17 +0900 Sergey Senozhatsky wrote: >On (26/10/21 12:23), Hillf Danton wrote: >> On Wed, 21 Oct 2026 11:42:19 +0900 Sergey Senozhatsky wrote: >> > Split struct zcomp_strm into separate compression (Write zcomp_cstrm) >> > and decompression (Read zcomp_dstrm) streams, and split zcomp_ops >> > context creation/destruction into create_cctx/destroy_cctx and >> > optional create_dctx/destroy_dctx callbacks. >> > >> > This decouples Read (decompression) and Write (compression) paths so >> > they no longer contend on the same per-CPU stream mutex (Writer vs >> > Reader priority inversion). Currently, a (low priority) Writer that >> > holds the stream mutex can be preempted by a (higher priority) Reader >> > on the same CPU, which then blocks on that mutex until the Writer gets >> > to run again and releases it, which can take a long time when there >> > are other runnable tasks on that CPU. >> > >> Given lock like mutex, priority inversion happens from Monday to Friday, >> but I wonder if you are inventing some wheels in 2026 if proxy excution >> works for you. > > Reader-Writer split is a foundation for further improvements (like > singleton recompression stream and so on). > But that split is not needed at all if PE works, yes?