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Mon, 7 Oct 2019 14:58:29 +0000 (UTC) Subject: Re: [PATCH 0/4] Add xxhash64 and sha256 as possible new checksums To: Johannes Thumshirn , David Sterba Cc: Linux BTRFS Mailinglist References: <20191007091104.18095-1-jthumshirn@suse.de> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: <2cf5e517-0c2e-87f9-45b4-6d0b2a04af25@suse.com> Date: Mon, 7 Oct 2019 17:58:27 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191007091104.18095-1-jthumshirn@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 7.10.19 г. 12:11 ч., Johannes Thumshirn wrote: > This series adds support for two additional checksum algorithms to btrfs. These > algorithms are xxhash64[1] and sha256[2]. > > xxhash64 is a fast non-cryptographic hash function with good collision resistance. > It has a constant output length of 8 Byte (64 Bit), it provides a good > trade-off between collision resistance and speed compared to the currently > used crc32c. > > sha256 is the 32 Byte (256 Bit) variant of the SHA-2 cryptographic hash. It > provides cryptographically secure collision resistance with a trade off in > speed. > > Support for xxhash64 in mkfs.btrfs is in the current devel branch and sha256 > support will be sent separately after this patch-set. > > In addition to adding these two hash algorithms two sysfs files are > implemented, one being /sys/fs/btrfs/features/supported_checksums showing the > in kernel support for different checksumming algorithms. The other one is > /sys/fs/btrfs/$FSID/checksum showing the checksum used for a specific > file-system and the used in-kernel driver for this checksum. > > Here is an example in a qemu vm: > host:/# cat /sys/fs/btrfs/features/supported_checksums > crc32c, xxhash64, sha256 > host:/# cat /sys/fs/btrfs/3cf09516-5bb8-498f-834d-e9ec54043546/checksum > sha256 (sha256-generic) > > This series has survived the usual regression testing with xfstests. > > I could not observe any performance differences between any of these hashes in > my test setup 256K mixed read-write IO to a single file from a single process > on both a 5700rpm SATA 3G Disk behind a HPE SmartArray RAID HBA and RAM Disk. > > Here's the raw numbers for the spinning rust behind SATA: > CRC32C Buffered Read (KiB/s): Avg: 7881, Min: 7495, Max: 8744, Stdev: 508 > CRC32C Buffered Write (KiB/s): Avg: 7883, Min: 7497, Max: 8746, Stdev: 508 > > CRC32C Direct Read (KiB/s): Avg: 331, Min: 319, Max: 339, Stdev: 7 > CRC32C Direct Write (KiB/s): Avg: 331, Min: 319, Max: 339, Stdev: 7 > > XXHASH64 Buffered Read (KiB/s): Avg: 8143, Min: 7748, Max: 8721, Stdev: 355 > XXHASH64 Buffered Write (KiB/s): Avg: 8145, Min: 7750, Max: 8722, Stdev: 355 > > XXHASH64 Direct Read (KiB/s): Avg: 311, Min: 248, Max: 336, Stdev: 36 > XXHASH64 Direct Write (KiB/s): Avg: 311, Min: 248, Max: 336, Stdev: 36 > > SHA256 Buffered Read (KiB/s): Avg: 7997, Min: 7665, Max: 8336, Stdev: 273 > SHA256 Buffered Write (KiB/s): Avg: 7998, Min: 7666, Max: 8337, Stdev: 273 > > SHA256 Direct Read (KiB/s): Avg: 312, Min: 248, Max: 336, Stdev: 36 > SHA256 Direct Write (KiB/s): Avg: 312, Min: 248, Max: 336, Stdev: 36 > > The reason I could not observe any changes in performance is the fact that the > btrfs checksumming process takes only 0.04% of the IO path. This also explains > the very small standard deviation in the above table as I stooped benchmarking > after 5 benchmark runs. > > The hottest call chain (according to perf) is this: > > 17.08% 0.00% kworker/u128:9- [kernel.vmlinux] [k] btrfs_finish_ordered_io > | > ---btrfs_finish_ordered_io > | > --17.04%--insert_reserved_file_extent.constprop.75 > | > --17.02%--__btrfs_drop_extents > | > --16.94%--btrfs_free_extent > | > --16.94%--btrfs_add_delayed_data_ref > | > --16.90%--btrfs_qgroup_trace_extent_post Yeah, we know qgroups tracing and backrefs resolv are somewhat slow. How about benchmarking without them since I believe this to be more representative of how people use btrfs. > btrfs_find_all_roots > | > --16.90%--btrfs_find_all_roots_safe > | > --16.89%--find_parent_nodes > | > --16.68%--resolve_indirect_refs > [snip] > > [1] https://cyan4973.github.io/xxHash > [2] https://en.wikipedia.org/wiki/SHA-2 > > David Sterba (1): > btrfs: sysfs: export supported checksums > > Johannes Thumshirn (3): > btrfs: add xxhash64 to checksumming algorithms > btrfs: add sha256 to checksumming algorithms > btrfs: show used checksum driver per filesystem in sysfs > > fs/btrfs/Kconfig | 2 ++ > fs/btrfs/ctree.c | 7 ++++++ > fs/btrfs/ctree.h | 2 ++ > fs/btrfs/disk-io.c | 2 ++ > fs/btrfs/super.c | 2 ++ > fs/btrfs/sysfs.c | 48 +++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/btrfs_tree.h | 2 ++ > 7 files changed, 65 insertions(+) >