0b9df58b79
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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| .. | ||
| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
| dt-bindings | ||
| keys | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| scsi | ||
| soc | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| video | ||
| xen | ||