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Thu, 10 Mar 2022 12:58:04 +0000 (GMT) Received: from [192.168.8.130] (106.210.248.212) by CAMSVWEXC01.scsc.local (2002:6a01:e347::6a01:e347) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 10 Mar 2022 12:57:59 +0000 Message-ID: Date: Thu, 10 Mar 2022 13:57:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH 0/6] power_of_2 emulation support for NVMe ZNS devices Content-Language: en-US To: Christoph Hellwig CC: Luis Chamberlain , Adam Manzanares , =?UTF-8?Q?Javier_Gonz=c3=a1lez?= , , kanchan Joshi , Jens Axboe , Keith Busch , Sagi Grimberg , =?UTF-8?Q?Matias_Bj=c3=b8rling?= , Pankaj Raghav , Kanchan Joshi , , , "Damien Le Moal" From: Pankaj Raghav In-Reply-To: <20220310094725.GA28499@lst.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [106.210.248.212] X-ClientProxiedBy: CAMSVWEXC01.scsc.local (2002:6a01:e347::6a01:e347) To CAMSVWEXC01.scsc.local (2002:6a01:e347::6a01:e347) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrPKsWRmVeSWpSXmKPExsWy7djPc7p3vmomGeyfqG+x+m4/m8Xvs+eZ LVauPspk0XPgA4vF+beHmSwmHbrGaLH3lrbF/GVP2S0mtH1ltrgx4SmjxZqbT1ks1r1+z+LA 4/HvxBo2j52z7rJ7nL+3kcXj8tlSj02rOtk8Ni+p99h9swEo13qf1ePzJjmP9gPdTAFcUVw2 Kak5mWWpRfp2CVwZG5Z+Zy5YwVux7MlmtgbGPVxdjBwcEgImErPuSncxcnEICaxglFi/cwMb hPOFUWLOlt8sEM5nRomDJ76ydjFygnVMeT0PKrGcUeJ1D0wLUNWfqSeZIZzdjBJb5n5nBmnh FbCTOL38LwuIzSKgKrH6yDI2iLigxMmZT8DiogIREi+P/GUCsYUFvCQ63q5lB7GZBcQlbj2Z DxYXEVCSePrqLCPIAmaB/SwSC3q6WUG+YBPQkmjsBKvnFNCRmNe/gwWiV1OidftvqDnyEtvf zmGGeFpZ4vV6G4hvaiXWHjvDDjJSQuAwp8TkOc3sEAkXiTe3zkO9LCzx6vgWqLiMxP+dIPeA NPQzSkxt+QPlzGCU6Dm8mQlig7VE35kciAZHif/fp7FChPkkbrwVhLiHT2LStunMExhVZyEF xSwkL89C8sIsJC8sYGRZxSieWlqcm55abJyXWq5XnJhbXJqXrpecn7uJEZjmTv87/nUH44pX H/UOMTJxMB5ilOBgVhLhbQrVSBLiTUmsrEotyo8vKs1JLT7EKM3BoiTOm5y5IVFIID2xJDU7 NbUgtQgmy8TBKdXAtNFJM+xxyWyX418jTptcnXeevazF0YCRk7W47lOF4WXjtISOxvU+VdpS wkc36yzfvl1i1WydJ3PT95pxWie6dn9rfbW254AHR+PfzHlvbWvmb7RZIrXHOKlA3p+JXeqq g6eteqLQrM0lqY/nb7i14nHoz51Nc7UPNVmLffDnsAo0joi5w5Yx5crsX2+iJBkVf/HHXol7 6hDm/Wz2F9Hgqkbn9M9Vxxef3h5VOb024P6vhPTFk/jdp8lKOMSe/7Jdst3+kMS7EJ+Mo90W s+94cedeXHe22GvSMvfv/IWnTn4/luuboZkaJrv35SwpZyVH+169wz2nYgKr+iONS5//MXmw M75LRjvx5t5IfwclluKMREMt5qLiRABGbVtX4gMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpmleLIzCtJLcpLzFFi42I5/e/4Xd07XzWTDPY3cFqsvtvPZvH77Hlm i5WrjzJZ9Bz4wGJx/u1hJotJh64xWuy9pW0xf9lTdosJbV+ZLW5MeMposebmUxaLda/fszjw ePw7sYbNY+esu+we5+9tZPG4fLbUY9OqTjaPzUvqPXbfbADKtd5n9fi8Sc6j/UA3UwBXlJ5N UX5pSapCRn5xia1StKGFkZ6hpYWekYmlnqGxeayVkamSvp1NSmpOZllqkb5dgl7GhqXfmQtW 8FYse7KZrYFxD1cXIyeHhICJxJTX81i6GLk4hASWMkqsObCJCSIhI/Hpykd2CFtY4s+1LjYQ W0jgI1DRUw6Iht2MEvN2PQBL8ArYSZxe/pcFxGYRUJVYfWQZVFxQ4uTMJ2BxUYEIibZlU5hB bGEBL4mOt2vBFjALiEvcejIfbLGIgJLE01dnGUEWMAvsZ5FY0NPNCrFtA6PE3E/rgKZycLAJ aEk0doI1cwroSMzr38ECMUhTonX7b6ih8hLb385hBimXEFCWeL3eBuKZWolX93czTmAUnYXk vFlIzpiFZNIsJJMWMLKsYhRJLS3OTc8tNtIrTswtLs1L10vOz93ECEwN24793LKDceWrj3qH GJk4GA8xSnAwK4nwNoVqJAnxpiRWVqUW5ccXleakFh9iNAWG0URmKdHkfGByyiuJNzQzMDU0 MbM0MLU0M1YS5/Us6EgUEkhPLEnNTk0tSC2C6WPi4JRqYNpbf0FG0fWe5P91P1lVvq9ssUz5 tOBMo/pCp0jGzbMcg/+1hByZ+GrRgxUeU0MmJys/XpZdxC39i01cc90sLZ9rNUk3GEV4XjwK unP3uVL4FNVb20+tKzinFzo/JP6wX/nP5ZYHOQPPW4hJCSgefbWk7vmVFeyBLgXmVz7sCvZP iWNsXSq3JrIq4eJt88nKtj29W2bdWnIuJGi3oL3gzm5jn1O2ph/d1xtu8dzCKvvB2iT/S+PM nT9lP256Xv256+2uu5+cb1+orxKQFl7tBgwJ1yhr1tPf+XsLjyzctXi/scn2jXYpjur8m7bu L10qEFi6OKwujj/KhKMjbcX0rf+Lbu++V3VDk3XulJv6uUosxRmJhlrMRcWJACHY9F2WAwAA X-CMS-MailID: 20220310125804eucas1p15d910568be986b2636b31f475cff891b X-Msg-Generator: CA X-RootMTR: 20220308165414eucas1p106df0bd6a901931215cfab81660a4564 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20220308165414eucas1p106df0bd6a901931215cfab81660a4564 References: <20220308165349.231320-1-p.raghav@samsung.com> <20220310094725.GA28499@lst.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220310_045808_006243_26C9A80A X-CRM114-Status: GOOD ( 22.49 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 2022-03-10 10:47, Christoph Hellwig wrote: > This is complete bonkers. IFF we have a good reason to support non > power of two zones size (and I'd like to see evidence for that) we'll non power of 2 support is important to the users and that is why we started this effort to do that. I have also CCed Bo from Bytedance based on their request. > need to go through all the layers to support it. But doing this emulation > is just idiotic and will at tons of code just to completely confuse users. > I agree with your point to create the non power of 2 support through all the layers but this is the first step. One of the early feedback that we got from Damien is to not break the existing kernel and userspace applications that are written with the po2 assumption. The following are the steps we have in the pipeline: - Remove the constraint in the block layer - Start migrating the Kernel applications such as btrfs so that it also works on non power of 2 devices. Of course, we wanted to post RFCs to the steps mentioned above so that there could be a public discussion about the issues. > Well, apparently whoever produces these drives never cared about supporting > Linux as the power of two requirement goes back to SMR HDDs, which also > don't have that requirement in the spec (and even allow non-uniform zone > size), but Linux decided that we want this for sanity. > > Do these drives even support Zone Append? Yes, these drives are intended for Linux users that would use the zoned block device. Append is supported but holes in the LBA space (due to diff in zone cap and zone size) is still a problem for these users. -- Regards, Pankaj