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Thu, 13 Nov 2025 15:55:20 +0800 X-QQ-mid: xmsmtpt1763020520t39bf1js8 Message-ID: X-QQ-XMAILINFO: OWROGFTRp+d+cprrP6KWNZeBoDbPIt355KIOdz7m8YO0yifwHSmyC318L/1UFM HQjK+iAcQMCwKSjbrPtsC5tB5a8AQ5NdkcSrP9g4SAB5M4UIEHZO06KxjpYRmJAc8xTyuCg9LlGq 2cIfEHotv7sPvLZW9Yj4KYRmoGTTswTwG0SgP3lychboOjo5ANiK8wtzYXpws2pqEPNivta748i6 pSvYwiaYLC2r1eyW5Rqi+/wasPYhDwZtFVo2Ctc3S5WKG3tXDd2l948ROigBSTe8pNiBWqNo9J7P Y+YOGhxBUiansipAfh862fXC9tuiIa/mY2XrqH43W/GdLREfobKISqlXBaXB7z0Isfew4KXbXNPw Bp8ihfv828SMU/k4BGO6GbV3ZgitsyvLzxgpBzKP5Ug6bEOQnbY3hwRmm00qedwc5cgyQQOonmJu TJwybxJcPuiXot9KClyFQ+YytKvS+XeyWU55jbgPwR5yev3JeIjtAS//4Hsl7DxZO2M2rohbge6F MjdmlR0esGEzMoTaZ4i8wS2kIPOMTSKZwK3vZMwSqVv9nRgWTxhiCAoD+tP2tDRzf6sOntmyKyE2 YbtwkgagBwt7zxLZc+4tiO2LoIFyTPN2PSo4DiheTdf1Okc/l7mE9Q/qzGCb/bD/XWE/L8U7B2Uu UTIrycqxeiWo2kjQduzJk5FTavIWDSqN9UBHxos8docNkd9idrMfClQ0kOLAEMD5BHe36JHivPPi 5k/ACopMxuB8EB/rXIY7TexiAC8A6i3+L9MNdk3R7bURVbPE37d42w6u2tDPNXLw7vJBXemPUqTc 1t8w4B7KS1kpPOmBItMQdSwu5CjAn7s8wVRhMaU4O0bxG69jT90Sbz4p8IFDchKKbz034dKP3rb/ Q80MXqdJo7lTocENwm7HbaajYcVZ4H2EBaR6cPsVcCzUrveJxFkDWnb7bVpbg+fymO0RbL8Bv0N/ r2L4NYeTwjWJWIJVdq48tDELGZB4kCw8t+ybRkOGzVoGGROUCB4LyoTCunSIB7PdGXNtLybsLrr/ v6cBaZZ+j8xXLec9dlGuqjcy/Hy+vJNlEjD2lRRg3+OgfGG38g X-QQ-XMRINFO: OD9hHCdaPRBwq3WW+NvGbIU= From: Yuwen Chen To: senozhatsky@chromium.org Cc: akpm@linux-foundation.org, axboe@kernel.dk, bgeffon@google.com, licayy@outlook.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, liumartin@google.com, minchan@kernel.org, richardycc@google.com, ywen.chen@foxmail.com Subject: Re: [PATCH v4] zram: Implement multi-page write-back Date: Thu, 13 Nov 2025 15:55:20 +0800 X-OQ-MSGID: <20251113075520.3325126-1-ywen.chen@foxmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 1amu83pje7to9fa4f58rsd6c144npit7 X-Rspam-User: X-Rspamd-Queue-Id: 945BE40002 X-Rspamd-Server: rspam10 X-HE-Tag: 1763020527-410774 X-HE-Meta: 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 T4D36xqb Q5H2cNYwvPRQDbvRcjOUkBEXEn00KeW80t6cOOlMrlj/71+rvjhAwbVPEoZyjnIqVNvMbcrnFink6qvg6fauNEPfjouwV/jgz78/quWNEHwJVGIG9+thtc3TxTF0kZfxGWE83O1XXBACKwafsUNUzJq8Hju/z44OePQfNG4D4vBXsiRB9TlP8eS32hXZPfX8PbrOgIsmZqts79MOQdxZKjBe+PA== 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 Thu, 13 Nov 2025 11:04:04 +0900, Sergey Senozhatsky wrote: > How was this number chosen? Did you try lower/higher values? > I think we might want this to be runtime tunable via sysfs, e.g. > writeback_batch_size attr, with min value of 1. I haven't conducted any tests on this value. I just set an empirical value of 32 based on the submission queue length of the storage device. As you said, providing a sys node for configuration might offer performance advantages for mechanical hard drives. On Thu, 13 Nov 2025 11:20:15 +0900, Sergey Senozhatsky wrote: > So I wonder if things will look simpler (is this the word I'm looking > for?) if you just have two lists for requests: one list for completed/idle > requests and one list for in-flight requests (and you move requests > around accordingly). Then you don't need to iterate the pool and check > flags, you just can check list_empty(&idle_requests) and take the first > (front) element. Yes, using two linked lists can reduce the complexity. It's just that before I saw your submission, I couldn't find a better way to avoid introducing locks. Thank you very much!