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Fri, 14 Nov 2025 19:42:18 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:b069:973b:b865:16a1]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2985c245da0sm69774885ad.26.2025.11.14.19.42.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 19:42:17 -0800 (PST) Date: Sat, 15 Nov 2025 12:42:12 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , Yuwen Chen , Richard Chang , Brian Geffon , Fengyu Lian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org Subject: Re: [PATCHv2 1/4] zram: introduce writeback bio batching support Message-ID: References: <20251113085402.1811522-1-senozhatsky@chromium.org> <20251113085402.1811522-2-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: e69p6xrs5kozamfziae4gym4k9k8u8r1 X-Rspam-User: X-Rspamd-Queue-Id: A5F70140004 X-Rspamd-Server: rspam01 X-HE-Tag: 1763178139-783540 X-HE-Meta: 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 xHTEuZQq ed/5nWc1ZO3wiHyUIrWXPoAL79wuzakEOtS2N+gy2/cQ9FAOgCfwDr/3MUoHaOavVkeWizHyL1rDjURGs1PB2wVqs6gm4MVI9UQgSAx9uaDbJYPcKzSB8M8tCmGTW8j+GgQbdzH6F3m6Uifumse02LrSbHZ4WryUHnlWoFCSDN//YJvWbGBcWVfah/PBKIM/c0WtWBD6CdyadesZ4sLN+8AA3nJUyNyQ7cZY6FbM+7g3tWlh2BiSVoeu+P0mSygNWAVwSJQxxJKVZbwEqvXW3fK3hondKCW1i+EUdI7q6FLCFk+rKChHDhf42+us6HF3nADqOGU3EPseyia4XDjZ9JA4cWK9jSJnrsNI+nxkJ/9aBB5w= 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 (25/11/14 11:14), Minchan Kim wrote: [..] > First, this writeback_store path is not critical path. Typical usecase > is trigger the writeback store on system idle time to save zram memory. One thing to note here, is that this is likely the case for embedded devices (smartphones, laptops, etc), where zram is often used as swap device. However, on servers (or desktops), zram can be used as a general purpose block device, and writeback can be executed under very different conditions there. Writeback is guaranteed to save memory, while on servers there might be no "idle time", so I can see scenarios when writeback is executed under load.