RFR: 8310159: Bulk copy with Unsafe::arrayCopy is slower compared to memcpy [v4]

[Jatin Bhateja]

On Thu, 16 Nov 2023 21:26:47 GMT, Steve Dohrmann <duke at openjdk.org> wrote:

>> Below is baseline data collected using a modified version of the java.lang.foreign.xor micro benchmark referenced by @mcimadamore  in the bug report.  I collected data on an Ubuntu 22.04 laptop with a Tigerlake i7-1185G7, which does support AVX512. 
>> 
>> Baseline data
>> Benchmark     (arrayKind)  (sizeKind)  Mode  Cnt           Score          Error  Units
>> --------------------------------------------------------------------------------------
>> XorTest.copy     ELEMENTS       SMALL  avgt   30   584737355.767 ± 60414308.540  ns/op
>> XorTest.copy     ELEMENTS      MEDIUM  avgt   30   272248995.683 ±  2924954.498  ns/op
>> XorTest.copy     ELEMENTS       LARGE  avgt   30  1019200210.900 ± 28334453.652  ns/op
>> XorTest.copy       REGION       SMALL  avgt   30     7399944.164 ±   216821.819  ns/op
>> XorTest.copy       REGION      MEDIUM  avgt   30    20591454.558 ±   147398.572  ns/op
>> XorTest.copy       REGION       LARGE  avgt   30    21649266.051 ±   179263.875  ns/op
>> XorTest.copy     CRITICAL       SMALL  avgt   30       51079.357 ±      542.482  ns/op
>> XorTest.copy     CRITICAL      MEDIUM  avgt   30        2496.961 ±       11.375  ns/op
>> XorTest.copy     CRITICAL       LARGE  avgt   30         515.454 ±        5.831  ns/op
>> XorTest.copy      FOREIGN       SMALL  avgt   30     7558432.075 ±    79489.276  ns/op
>> XorTest.copy      FOREIGN      MEDIUM  avgt   30    19730666.341 ±   500505.099  ns/op
>> XorTest.copy      FOREIGN       LARGE  avgt   30    34616758.085 ±   340300.726  ns/op
>> XorTest.xor      ELEMENTS       SMALL  avgt   30   219832692.489 ±  2329417.319  ns/op
>> XorTest.xor      ELEMENTS      MEDIUM  avgt   30   505138197.167 ±  3818334.424  ns/op
>> XorTest.xor      ELEMENTS       LARGE  avgt   30  1189608474.667 ±  5877981.900  ns/op
>> XorTest.xor        REGION       SMALL  avgt   30    64093872.804 ±   599704.491  ns/op
>> XorTest.xor        REGION      MEDIUM  avgt   30    81544576.454 ±  1406342.118  ns/op
>> XorTest.xor        REGION       LARGE  avgt   30    90091424.883 ±   775577.613  ns/op
>> XorTest.xor      CRITICAL       SMALL  avgt   30    57231375.744 ±   438223.342  ns/op
>> XorTest.xor      CRITICAL      MEDIUM  avgt   30    58583884.930 ±   375355.215  ns/op
>> XorTest.xor      CRITICAL       LARGE  avgt   30    60644832.949 ±   588120.738  ns/op
>> XorTest.xor       FOREIGN       SMALL  avgt   30    73868679.405 ±   819965.524  ns/op
>> XorTest.xor       FOREIGN      MEDIUM  avgt   30    88156275.944 ±  1051257.152  ns/op
>> Xo...
>
> Steve Dohrmann has updated the pull request incrementally with one additional commit since the last revision:
> 
>   - fix whitespace error

Hi @steveatgh , X86 code changes looks good to me.

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Marked as reviewed by jbhateja (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16575#pullrequestreview-1740295564