Hi, my 2 cents, (I miss some CC because i don't have a copy of mail i found conversation on: http://www.spinics.net/lists/linux-mm/msg132431.html) (Fix me if i'm wrong, may be i miss something) So, I have a Skylake with HW SHA1/256 And i use openssl 1.1.0.f for testing Hash 1GiB file for throughput testing. No HW sha1 (Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz) - sha1 - ~300 MiB/s - sha256 - ~128 MiB/s Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz - sha1 - ~900 MiB/s - sha256 - ~350 MiB/s CRC32C for example below show about 13650.720367 MiB/s I'm also afraid about possible collisions, but AFAIK: http://cyan4973.github.io/xxHash/ (I copy part of table from that page) Name Speed Quality Author xxHash 5.4 GB/s 10 Y.C. Lookup3 1.2 GB/s 9 Bob Jenkins CRC32 0.43 GB/s 9 (that a SW implementationt, let's ignore speed) So (in theory of course) jhash2 and crc32 have a same problems with collisions. Info from my patch set (replace jhash2 with xxhash) x86_64 host: CPU: Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz PAGE_SIZE: 4096, loop count: 1048576 jhash2: 0xacbc7a5b time: 1907 ms, th: 2251.9 MiB/s xxhash32: 0x570da981 time: 739 ms, th: 5809.4 MiB/s xxhash64: 0xa1fa032ab85bbb62 time: 371 ms, th: 11556.6 MiB/s CPU: Intel(R) Xeon(R) CPU E5-2420 0 @ 1.90GHz PAGE_SIZE: 4096, loop count: 1048576 jhash2: 0xe680b382 time: 3722 ms, th: 1153.896680 MiB/s xxhash32: 0x56d00be4 time: 1183 ms, th: 3629.130689 MiB/s xxhash64: 0x8c194cff29cc4dee time: 725 ms, th: 5918.003401 MiB/s So i really not believe in sha1 for KSM, it's just to slow Thanks. -- Have a nice day, Timofey. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
