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AJvYcCXH2U41DMG2X9hmzpXFLiLREYDAUPirnZDeaPLY20mcAoTKyNbkoPfEbm7M1kEfGaAb/bTXy0AgrHkkVvPIidQ//zY= X-Gm-Message-State: AOJu0YxudvZwYNfs8z9DIxqc9F+x0HO5eGANBjJnTmWypUI+HsKtvnPK EesG6KWjCoBWKxg2ETHUJPfbPvhAruTmM5jZSX6JKDPfD8lzjub7acH61Mx4Xrqd2xf6glzhFde KL/vn2DEhWn0Us+jzGm1/PKJPoQw= X-Google-Smtp-Source: AGHT+IGwYg82We3uLuR2mZ/xbiWuGjRpwEPg+Yy/6af9O3ukcvNdq4tIg71vISFu90ZIh+8muwTg9jg1Bla+rXCh2xI= X-Received: by 2002:a05:6512:38d1:b0:51f:1853:25f with SMTP id 2adb3069b0e04-5220fc79467mr2836408e87.19.1715412920609; Sat, 11 May 2024 00:35:20 -0700 (PDT) MIME-Version: 1.0 References: <20240509023937.1090421-1-zhaoyang.huang@unisoc.com> <20240509023937.1090421-3-zhaoyang.huang@unisoc.com> In-Reply-To: From: Zhaoyang Huang Date: Sat, 11 May 2024 15:35:09 +0800 Message-ID: Subject: Re: [RFC PATCH 2/2] mm: introduce budgt control in readahead To: Matthew Wilcox Cc: "zhaoyang.huang" , Andrew Morton , Jens Axboe , Tejun Heo , Josef Bacik , Baolin Wang , linux-mm@kvack.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, steve.kang@unisoc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: g1q5hjyw4wgs4wjutz31bed1rg4wp5g1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: AFD621A000F X-HE-Tag: 1715412922-954568 X-HE-Meta: U2FsdGVkX1+wurz+bsokIw+DF89tiB38wL63XHewFeTPHu4pq5q3mj5Q0Tp5N2TsofC+HWmImZBqP4PdgnJu1ndb6wmW3VanDW8Lgwqo4Sw06bcrhPna06CvSjjm27jMUnHPQIdO/Ln9gKZsLJARidKIo1crtpyqz+aUt7OvOim2f9hYEvdLtHxKesOHhL36E8stxV+32e82DKf78AjB/QOJLsLdQmEpmw8sgargnjTGAft8M6XVO6RJFJMNUqzzVzV2rMsLC+mTbOCS88ceCgXH74tDH4CAHTuX+MPCU6lyk+rhb4z4UlXTHIcXnGdRpeUcLHg62SrN2TLk3lY6W7NQI/rwMRpttoGnTYNkfw4LEXg7GZ0j14jI4WxmzWY7dT2kE+nlwWygWxPc5/JXUgSoXQ2EFKB2TE/Lb1SGZxuKkMsHRRhHd8YVvjVMc521dS58bO7xZ2gIx/YkwfpSvofejClpgphGcvMwz5xrGmZ6vmwC0phWusoF0NMzMRNGgiz+BQFqc1QtZzYkoxn9ZGnEUGtjVCdPIju3+BVd7w0TNF+eUxrLRSRB86VxEKFVKh+FGxivwB9/yDFQNVjctMsReW5dxSTI8yeK5H8Ow0bDhzdSvjBBycY7hduKUAj1jqTnE8TbPe1+7IRgTmI466IF/3Eh9LUZIVU0YtPfrCKzNahlPalw8GVg9h5Yf3iHlarDPUNbpkNFHeO7ct7CeXFXs0DXU6G017QqETq2ZxVKa4NK5iMjHpBDB6m95PvN0QZa9HvuXcEUSqcirnfYQ2f7zcr9IAFE6ztOeAAyEPmRl+KXMBoHm9v/Iqjt2mxk9gCP7a/T2uVMwLQmBV+huI8pK3XQRTpgcxYnlQX5Wu7iGt6JsHul/XYMXNLhopFBdVJk1Xv3Lf5QBa1PMrmQQXau85hOFSKBbux3zgwTwuBOeYebJYoVd7l8AMWSBaS7o87MSnjRgeqO5u5NMnG RqrORtF7 0aNSszeXDkeBpCaZtAWQxlIllI4dWSfEPa8TQ/VZXALotZ/dXMMvzu7dFGz7l9BMIdXkqXvetWb/cpzdRIuhI5uFXzr/3xgB8VjUzxcU26XKWjzYpAAoJRWthvCnI+Q4aMEDg/LVQ7ZVi900d9KcVacBCaGUY8k/WGmrwnW1jL/CQg7FL1PmYKlxdnPgy9wGiNXwyeH3sX8bkUSbsnUYSvpHtCKvJbBkBm3jZe7Eu5yX3rgu3T1dLZ8Cky5vgmkq9A78ZhjNf52NvrdkL1GhyEYxy4bhTWdGxqmVqdfx0hedecY6aIv/QHNtccpkm9rpYaLLbrjs18hOaUfCUiXYaoMgNh3PDtzHW7gG0jsSbL+r9Dq97RsxGGyZSBcKvTQXMXD4mdhorZjZcfLWKCkdr6Du0YYEsiXlWZUIe 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 Fri, May 10, 2024 at 11:18=E2=80=AFAM Matthew Wilcox wrote: > > On Fri, May 10, 2024 at 10:43:20AM +0800, Zhaoyang Huang wrote: > > Thanks for the prompt. I did some basic research on soft RAID and > > wonder if applying the bps limit on /dev/md0 like below could make > > this work. > > No. Look at btrfs' raid support, for example. it doesn't use md0. If I understand the below command correctly, btrfs uses one of the volumes within RAID as the mount block device, not /dev/md0. However, I think this is a problem of blkio.throttle rather than this commit which means this readahead budget control will work accordingly as long as blkio.throttle's parameter is configured correctly(eg. 50/50 on sdb and sdc) mkfs.btrfs -m raid0 -d raid0 /dev/sdb /dev/sdc mount -t btrfs /dev/sdb /mnt/btr > > > I didn't find information about 'RAID internally'. Could we set the > > limit on the root device(the one used for mount) to manage the whole > > partition without caring about where the bio finally goes? Or ask the > > user to decide if to use by making sure the device they apply will not > > do RAID? > > No.