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https://issues.apache.org/jira/browse/CASSANDRA-2975?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13153112#comment-13153112
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David Allsopp commented on CASSANDRA-2975:
------------------------------------------
The benchmark does several rounds of warmup for each iteration (i.e. for each
buffer size from 1 to 32 bytes).
It reduces the number of iterations as the input buffer size grows, so that
each run processes a similar number of bytes - though this is probably
irrelevant since the performance seems fairly constant with respect to buffer
size.
{noformat}
Running test for buffer lengths from 1 to 32
*| Ratio: 0.96 for keylength 1 iterations=100000000
*| Ratio: 0.95 for keylength 2 iterations=50000000
*| Ratio: 0.95 for keylength 3 iterations=33333333
*| Ratio: 0.96 for keylength 4 iterations=25000000
*| Ratio: 0.94 for keylength 5 iterations=20000000
*| Ratio: 0.94 for keylength 6 iterations=16666666
*| Ratio: 0.96 for keylength 7 iterations=14285714
*| Ratio: 0.93 for keylength 8 iterations=12500000
* | Ratio: 0.89 for keylength 9 iterations=11111111
*| Ratio: 0.93 for keylength 10 iterations=10000000
*| Ratio: 0.95 for keylength 11 iterations=9090909
*| Ratio: 0.95 for keylength 12 iterations=8333333
*| Ratio: 0.93 for keylength 13 iterations=7692307
*| Ratio: 0.90 for keylength 14 iterations=7142857
*| Ratio: 0.95 for keylength 15 iterations=6666666
* | Ratio: 0.86 for keylength 16 iterations=6250000
* | Ratio: 0.87 for keylength 17 iterations=5882352
*| Ratio: 0.91 for keylength 18 iterations=5555555
* | Ratio: 0.83 for keylength 19 iterations=5263157
* | Ratio: 0.83 for keylength 20 iterations=5000000
* | Ratio: 0.80 for keylength 21 iterations=4761904
* | Ratio: 0.88 for keylength 22 iterations=4545454
*| Ratio: 0.91 for keylength 23 iterations=4347826
*| Ratio: 0.91 for keylength 24 iterations=4166666
* | Ratio: 0.88 for keylength 25 iterations=4000000
*| Ratio: 0.92 for keylength 26 iterations=3846153
* | Ratio: 0.85 for keylength 27 iterations=3703703
* | Ratio: 0.88 for keylength 28 iterations=3571428
* | Ratio: 0.88 for keylength 29 iterations=3448275
* | Ratio: 0.89 for keylength 30 iterations=3333333
*| Ratio: 0.92 for keylength 31 iterations=3225806
--------
Old (ms): 18938
New (ms): 17470
Overall ratio: 0.9224838948146583
{noformat}
i.e. 8% improvement on average.
> Upgrade MurmurHash to version 3
> -------------------------------
>
> Key: CASSANDRA-2975
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2975
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Brian Lindauer
> Assignee: Brian Lindauer
> Priority: Trivial
> Labels: lhf
> Fix For: 1.1
>
> Attachments:
> 0001-Convert-BloomFilter-to-use-MurmurHash-v3-instead-of-.patch,
> 0002-Backwards-compatibility-with-files-using-Murmur2-blo.patch,
> Murmur3Benchmark.java
>
>
> MurmurHash version 3 was finalized on June 3. It provides an enormous speedup
> and increased robustness over version 2, which is implemented in Cassandra.
> Information here:
> http://code.google.com/p/smhasher/
> The reference implementation is here:
> http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp?spec=svn136&r=136
> I have already done the work to port the (public domain) reference
> implementation to Java in the MurmurHash class and updated the BloomFilter
> class to use the new implementation:
> https://github.com/lindauer/cassandra/commit/cea6068a4a3e5d7d9509335394f9ef3350d37e93
> Apart from the faster hash time, the new version only requires one call to
> hash() rather than 2, since it returns 128 bits of hash instead of 64.
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