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[209.85.218.42]) by smtp.gmail.com with ESMTPSA id r18-20020a170906365200b00a3efa4e033asm779480ejb.151.2024.02.24.10.24.34 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 24 Feb 2024 10:24:34 -0800 (PST) Received: by mail-ej1-f42.google.com with SMTP id a640c23a62f3a-a3f3d0d2787so166338266b.3 for ; Sat, 24 Feb 2024 10:24:34 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCVmqf46ufb+9hzUbxfsCzfaCQiVNQmDWNdVsaKfNm0tD8DK5cQmGrIBeYGtdiWDMzd0vPmi0TlFEDwq+fWHXjXfmhI= X-Received: by 2002:a17:906:6701:b0:a3f:6717:37ae with SMTP id a1-20020a170906670100b00a3f671737aemr2030241ejp.69.1708799073809; Sat, 24 Feb 2024 10:24:33 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Linus Torvalds Date: Sat, 24 Feb 2024 10:24:17 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [LSF/MM/BPF TOPIC] Measuring limits and enhancing buffered IO To: Matthew Wilcox Cc: Luis Chamberlain , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm , Daniel Gomez , Pankaj Raghav , Jens Axboe , Dave Chinner , Christoph Hellwig , Chris Mason , Johannes Weiner Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 9A376C0005 X-Rspam-User: X-Stat-Signature: apci53mgp53kieeaqogg9ooapyjs5dyx X-Rspamd-Server: rspam01 X-HE-Tag: 1708799076-244452 X-HE-Meta: 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 8OEqWYgM 7iCoV5cvrpf+vCghHGjSiE7I36yn7PAf0jKXsh+nGGbPZChpbKby6WfSj2s2/QAAfkB/I4dial1wMGS0Jqedjb5dTDUYFTDZC8ljO741QOkJhiYVo1N3jyqwke49zZ+KXVfNJkmzjttdhkDy9ZKAgx6lBASE/weYoFY7S5oTrl2OmsRlN+KZS869MXlvoK6iAUViPwppMosZUzwQiD95h3fA7vaSGQgpGswFqDGfrnqhhCb4sVhytML1LNoJS7ypKdO50Xxr3AsYp70A= 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 Sat, 24 Feb 2024 at 10:13, Matthew Wilcox wrote: > > > Ask yourself when you have last *really* sat there waiting for writes, > > unless it's some dog-slow USB device that writes at 100kB/s? > > You picked a bad day to send this email ;-) > > $ sudo dd if=Downloads/debian-testing-amd64-netinst.iso of=/dev/sda What? No. I literally picked the example you then did. And you in fact were being clueless, and the kernel damn well should tell you that you are being an ass, and should slow your writes down so that you don't hurt others. Which is what it did. You should have damn well used oflag=direct, and if you didn't do that, then the onus is all on YOU. The kernel really isn't there to fix your stupid errors for you. You do something stupid, the kernel will give you rope and happily say "do you want more?" Linus