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Wed, 07 Jan 2026 02:15:00 -0800 (PST) Received: from google.com ([2a00:79e0:2031:6:7bef:7c13:79b4:e9de]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3c4795fsm47255015ad.33.2026.01.07.02.14.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jan 2026 02:14:59 -0800 (PST) Date: Wed, 7 Jan 2026 19:14:54 +0900 From: Sergey Senozhatsky To: zhangdongdong Cc: Sergey Senozhatsky , Andrew Morton , Richard Chang , Minchan Kim , Brian Geffon , David Stevens , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, Minchan Kim Subject: Re: [PATCHv2 1/7] zram: introduce compressed data writeback Message-ID: References: <20251201094754.4149975-1-senozhatsky@chromium.org> <20251201094754.4149975-2-senozhatsky@chromium.org> <40e38fa7-725b-407a-917a-59c5a76dedcb@sina.com> <7bnmkuodymm33yclp6e5oir2sqnqmpwlsb5qlxqyawszb5bvlu@l63wu3ckqihc> <2663a3d3-2d52-4269-970a-892d71c966bb@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2663a3d3-2d52-4269-970a-892d71c966bb@sina.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5923A4000F X-Stat-Signature: w4twwbcqdxgtj3qhqswfniu4i9kb1ys1 X-Rspam-User: X-HE-Tag: 1767780901-739964 X-HE-Meta: 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 6yNtJP8a Oau7omUW0RNU3TeqKQ77ZaX/msZ2nFibAqFdCkP+tYHu/WGKF8LudLTxsiXiA79o2pP1Xp9iipucII8ngJSsdXk2RxXzkEVmycREoDX3pYIGFL+zSdbwTB/SNTe4XJkG6Qoubkj8pZRlyN9hF7exrBAhaDzq+WmVCnHX/CFHHfL76IrkRQO5+lfZ9wbUOImySayzhW5RNtQdC2NCP3tgeI/0Z7lTbp90mjPCbG4Te97XvR2jgcuLB3vNTlpBa+L2PJ1bcf21QXNklWIaE8UAcX7020mZYNBxpXJhclQL9vKxwFpo//ldBSVKXmjbDtlAMsc2AItmKVbX0f5GbKcOyvYp0fFHdJCA3VttkFlC1yd3HgqE= 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 15:28), zhangdongdong wrote: > Hi,Sergey > > Yes, we have tried high priority workqueues. In fact, our current > implementation already uses a dedicated workqueue created with > WQ_HIGHPRI and marked as UNBOUND, which handles the read/decompression > path for swap-in. > > Below is a simplified snippet of the queue we are currently using: > > zgroup_read_wq = alloc_workqueue("zgroup_read", > WQ_HIGHPRI | WQ_UNBOUND, 0); > > static int zgroup_submit_zio_async(struct zgroup_io *zio, > struct zram_group *zgroup) > { > struct zgroup_req req = { > .zio = zio, > }; > zgroup... That certainly looks like a lot of downstream code ;) Do you use any strategies for writeback? Compressed writeback is supposed to be used for apps for which latency is not critical or sensitive, because of on-demand decompression costs.