[9] RFR(XS) 8059780: SPECjvm2008-MPEG performance regressions on x64 platforms

[Vladimir Kozlov]

Thank you, Igor

Vladimir K

On 11/1/14 12:29 AM, Igor Veresov wrote:
> Looks fine to me.
>
> igor
>
> On Oct 31, 2014, at 2:55 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>
>> http://cr.openjdk.java.net/~kvn/8059780/webrev/
>> https://bugs.openjdk.java.net/browse/JDK-8059780
>>
>> We found performance regression (3-5%) on x64 after changes 8052081 [1] were pushed. It is caused by changes in lcm.cpp. Those changes were done because Atom is in-order cpu and some benchmarks on Atom showed benefit from these changes.
>>
>> But Atom is not our core platform and the regression is big.
>>
>> Backout changes made in lcm.cpp in jdk9 and 8u40 (8052081 was backported to 8u40).
>>
>> We have RFEs to improve block's instructions order which may help both platforms:
>>
>> https://bugs.openjdk.java.net/browse/JDK-6958833
>> https://bugs.openjdk.java.net/browse/JDK-7101232
>>
>> Tested with SPECjvm2008-mpegaudio.
>>
>> Thanks,
>> Vladimir
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8052081
>