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H A D | xxhash.h | 0b9df58b Fri Dec 28 08:34:00 GMT 2018 Timofey Titovets <nefelim4ag@gmail.com> xxHash: create arch dependent 32/64-bit xxhash()
Patch series "Currently used jhash are slow enough and replace it allow as to make KSM", v8.
Apeed (in kernel): ksm: crc32c hash() 12081 MB/s ksm: xxh64 hash() 8770 MB/s ksm: xxh32 hash() 4529 MB/s ksm: jhash2 hash() 1569 MB/s
Sioh Lee's testing (copy from other mail):
Test platform: openstack cloud platform (NEWTON version) Experiment node: openstack based cloud compute node (CPU: xeon E5-2620 v3, memory 64gb) VM: (2 VCPU, RAM 4GB, DISK 20GB) * 4 Linux kernel: 4.14 (latest version) KSM setup - sleep_millisecs: 200ms, pages_to_scan: 200
Experiment process: Firstly, we turn off KSM and launch 4 VMs. Then we turn on the KSM and measure the checksum computation time until full_scans become two.
The experimental results (the experimental value is the average of the measured values) crc32c_intel: 1084.10ns crc32c (no hardware acceleration): 7012.51ns xxhash32: 2227.75ns xxhash64: 1413.16ns jhash2: 5128.30ns
In summary, the result shows that crc32c_intel has advantages over all of the hash function used in the experiment. (decreased by 84.54% compared to crc32c, 78.86% compared to jhash2, 51.33% xxhash32, 23.28% compared to xxhash64) the results are similar to those of Timofey.
But, use only xxhash for now, because for using crc32c, cryptoapi must be initialized first - that require some tricky solution to work good in all situations.
So:
- First patch implement compile time pickup of fastest implementation of xxhash for target platform.
- The second patch replaces jhash2 with xxhash
This patch (of 2):
xxh32() - fast on both 32/64-bit platforms xxh64() - fast only on 64-bit platform
Create xxhash() which will pick up the fastest version at compile time.
Link: http://lkml.kernel.org/r/20181023182554.23464-2-nefelim4ag@gmail.com Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com> Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: leesioh <solee@os.korea.ac.kr> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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