RFR: 8131062: aarch64: add support for GHASH acceleration

[Vladimir Kozlov]

Looks good to me.

Thanks,
Vladimir

On 7/21/15 8:18 AM, Edward Nevill wrote:
> Hi,
>
> http://cr.openjdk.java.net/~enevill/8131062/webrev.0/
>
> adds support for GHASH acceleration on aarch64 using the 128 bit pmull and pmull2 instructions.
>
> This patch was contributed by alexander.alexeev at caviumnetworks.com
>
> Note that the 128 pmull instructions are not supported on all aarch64. The patch uses the HWCAP_PMULL bit from getauxv() to determine whether the 128 bit pmull is supported.
>
> I have tested this with jtreg / hotspot.
>
> Without patch: Test results: passed: 876; failed: 3; error: 9
> With patch: Test results: passed: 876; failed: 3; error: 9
>
> In both cases the set of failing/error tests is identical.
>
> I have done some performance testing using TestAESMain from the jtreg/hotspot test suite. Here are the results I get:-
>
> java -XX:-UseGHASHIntrinsics -DcheckOutput=true -Dmode=GCM TestAESMain
>
> encode time = 66945.63635, decode time = 34085.08754
>
> java -XX:+UseGHASHIntrinsics -DcheckOutput=true -Dmode=GCM TestAESMain
>
> encode time = 43469.38244, decode time = 17783.6603
>
> This is an improvement of 54% and 92% respectively.
>
> Alexander has done some benchmarking to measure the raw performance improvement of GHASH on its own using the following benchmark.
>
> http://cr.openjdk.java.net/~enevill/8131062/GHash.java
>
> Here are the results he gets:-
>
> -XX:-UseGHASHIntrinsics.
>
> Benchmark             Mode  Cnt    Score   Error  Units
> GHash.calculateGHash  avgt    5  118.688 ? 0.009  us/op
>
> -XX:+UseGHASHIntrinsics
> Benchmark             Mode  Cnt   Score   Error  Units
> GHash.calculateGHash  avgt    5  21.164 ? 1.763  us/op
>
> This represents a 5.6X speed increase on the raw GHASH performance.
>
> Thanks your your review,
>
> Ed.
>
>