From: "Holger Hoffstätte" <holger@applied-asynchrony.com>
To: Linux BTRFS Mailinglist <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH v2 0/4] Support xxhash64 checksums
Date: Thu, 22 Aug 2019 14:28:53 +0200 [thread overview]
Message-ID: <ed9e2eaa-7637-9752-94bb-fd415ab2b798@applied-asynchrony.com> (raw)
In-Reply-To: <20190822114029.11225-1-jthumshirn@suse.de>
On 8/22/19 1:40 PM, Johannes Thumshirn wrote:
> Now that Nikolay's XXHASH64 support for the Crypto API has landed and BTRFS is
> prepared for an easy addition of new checksums, this patchset implements
> XXHASH64 as a second, fast but not cryptographically secure checksum hash.
Question from the cheap seats.. :)
I know that crc32c-intel uses native SSE 4.2 instructions, but so far I have
been unable to find benchmarks or explanations why adding xxhash64 benefits
btrfs. All benchmarks seem to be against crc32c in *software*, not the
SSE4.2-enabled version (or I can't read). I mean, it's great that xxhash64 is
really fast for a software implementation, but how does btrfs benefit from this
compared to using crc32-intel?
Verifying that plugging in other hash impls works (e.g. as preparation for
stronger impls) has value, but it's probably not something most
users care about.
Maybe there are obscure downsides to crc32c-intel like instruction latency
(def. a problem for AVX512), cache pollution..?
Just curious.
thanks,
Holger
next prev parent reply other threads:[~2019-08-22 12:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 11:40 [PATCH v2 0/4] Support xxhash64 checksums Johannes Thumshirn
2019-08-22 11:40 ` [PATCH v2 1/4] btrfs: turn checksum type define into a enum Johannes Thumshirn
2019-08-22 11:40 ` [PATCH v2 2/4] btrfs: create structure to encode checksum type and length Johannes Thumshirn
2019-08-22 12:11 ` Johannes Thumshirn
2019-08-22 13:22 ` [PATCH v2.1] " Johannes Thumshirn
2019-08-22 11:40 ` [PATCH v2 3/4] btrfs: use xxhash64 for checksumming Johannes Thumshirn
2019-08-22 11:40 ` [PATCH v2 4/4] btrfs: sysfs: export supported checksums Johannes Thumshirn
2019-08-22 12:28 ` Holger Hoffstätte [this message]
2019-08-22 12:54 ` [PATCH v2 0/4] Support xxhash64 checksums Johannes Thumshirn
2019-08-22 15:40 ` Peter Becker
2019-08-23 9:38 ` Paul Jones
2019-08-23 9:43 ` Paul Jones
2019-08-23 17:08 ` Adam Borowski
2019-08-26 12:27 ` Austin S. Hemmelgarn
2019-08-27 0:33 ` Adam Borowski
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