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Wed, 26 Mar 2025 01:15:32 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:d343:29c5:4565:9d95]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-73905fab52csm11536233b3a.20.2025.03.26.01.15.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Mar 2025 01:15:32 -0700 (PDT) Date: Wed, 26 Mar 2025 17:15:28 +0900 From: Sergey Senozhatsky To: Richard Chang Cc: Sergey Senozhatsky , Minchan Kim , Andrew Morton , Brian Geffon , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] zram: modernize writeback interface Message-ID: References: <20250325034210.3337080-1-senozhatsky@chromium.org> <5l4pjqlgu4afndn3ysa7ynecjmvepkfjlh56ycm5jt5e4mioqm@dujakwaomhlk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BC9F51C000F X-Stat-Signature: rth7sbxq5kb694d3bncb11giwnjfb645 X-HE-Tag: 1742976933-684719 X-HE-Meta: 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 +fblv2aj zYSHrsa8dq1kSJjENpGQUhuVrCmB6OAOfXRTjRQ/s3N96D8VoUh1+gc7TS1WVXkcRn+as28H/rMXf1KZivk7fcgbQdNuXAPHqZCsg9CSXa8PZ4+2YggCrpQ6C7xuaisppypxRLRDbOGNXpNsNcWMLm8YDzO88vAZt3qendM4h6BAQY1fAD+roo62kMhjTxg2mQUhy17kZVuikM7FDxZQyDo0QLXH1H5lb4/2DxdTo+yc1y6mNxCMdBd5bsRgS4c3jJznPrvHl6RB4O5RwXRIVuIjY3zzb1dyOa7QNm94QcXbiQYPqWsDmzoTxxg/JpnwMuRZX3f4EyLGV66oDl803ko6Y3aOKzpCLUlZSLlh9CTagaxU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000132, 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 (25/03/26 15:07), Richard Chang wrote: > I am just counting how many pages we could writeback per syscall. > In a worst case, page_index_range with several two-adjacent indices: > Assume PAGE_SIZE is 4k and index range is around 10000, > > page_index_range allows 272 pages per syscall: > page_index_range=10000-10001 page_index_range=10003-10004... > > List_range allows 678 pages per syscall: > page_index_range=10000-10001,10003-10004... Page index can be u32, much longer than 10000. With really high indices you'd probably waste more space on "N-N+1" alone than on page_index=N. I'd say index-range should be used when there is a range to begin with. [..] > Another alternative thought, how about page_index supporting both > single instance and ranges? > The key is shorter and the parser is relatively simpler. > Eg: page_index=500 page_index=10000-10001 I probably can look into it.