RFR(XS): 8001424: G1: Rename certain G1-specific flags

John Cuthbertson john.cuthbertson at oracle.com
Fri Dec 21 10:46:35 PST 2012


Hi Bengt,

Great. The old names have been removed (they won't be accepted in either 
hs24 or hs25). This makes the changes a lot smaller. Your statement 
below was part of teh reason why I wanted them to stay experimental.

JohnC


On 12/21/2012 5:47 AM, Bengt Rutisson wrote:
>
> Hi John,
>
> On 12/20/12 7:04 PM, John Cuthbertson wrote:
>> Hi Ramki, Bengt,
>>
>> Thanks for the reviews. I kept the old names because the perf team 
>> would like these backported to hs24 (7u12) and the old names have 
>> been published in several presentation decks - including one from 
>> Monica and Charlie at JavaOne. Does it still make sense to just 
>> accept the new names? The change would be much smaller if so.
>
> Personally I would still not think we should keep the old names. After 
> all they are experimental flags.
>
> If we should keep the old names I think it would be enough to that in 
> hs24/7u12. I would prefer that we don't have the old names in JDK8.
>
> Thanks,
> Bengt
>
>>
>> Thanks,
>>
>> JohnC
>>
>> On 12/20/2012 1:19 AM, Srinivas Ramakrishna wrote:
>>> New names look good. I agree with Bengt that for renames of exptal 
>>> flags in a major release bothering supporting old names is not 
>>> worthwhile; best to
>>> make a clean break with the old names.
>>>
>>> reviewed
>>> -- ramki
>>>
>>> On Wed, Dec 19, 2012 at 10:30 PM, Bengt Rutisson 
>>> <bengt.rutisson at oracle.com <mailto:bengt.rutisson at oracle.com>> wrote:
>>>
>>>
>>>     Hi again John,
>>>
>>>     I realized that I was a bit too fast with my comment about using
>>>     ObsoleteFlag. Your code is aliasing the old names for the new
>>>     ones which is something the obsolete flag management does not do.
>>>
>>>     But on the other hand, do we really want to do this? These are
>>>     all experimental flags and we are pushing this change to a major
>>>     release, JDK8. Personally I don't think it is worth supporting
>>>     the old names.
>>>
>>>     Bengt
>>>
>>>
>>>     On 12/20/12 5:45 AM, Bengt Rutisson wrote:
>>>>
>>>>     Hi John,
>>>>
>>>>     This looks good. But I think that instead of your change in
>>>>     arguments.cpp you could make use of the obsolete_jvm_flags list
>>>>     that exist in the same file. I think that is intended for
>>>>     exactly this purpose. Accepting a removed flag name for a
>>>>     little while. The nice thing about it it that you specify how
>>>>     long you will accept the old name.
>>>>
>>>>     static ObsoleteFlag obsolete_jvm_flags[] = {
>>>>       { "UseTrainGC", JDK_Version::jdk(5), JDK_Version::jdk(7) },
>>>>
>>>>     If you use this you also have to remove the old flag names from
>>>>     globals.hpp.
>>>>
>>>>     Bengt
>>>>
>>>>
>>>>     On 12/20/12 1:56 AM, John Cuthbertson wrote:
>>>>>     Hi Everyone,
>>>>>
>>>>>     Some flag name changes suggested by the JVM performance team
>>>>>     based upon feedback they have received. The webrev can found
>>>>>     at: http://cr.openjdk.java.net/~johnc/8001424/webrev.0/
>>>>>     <http://cr.openjdk.java.net/%7Ejohnc/8001424/webrev.0/>
>>>>>
>>>>>     Basically the changes are those listed in the webrev:
>>>>>
>>>>>     G1DefaultMinNewGenPercent is being replaced by G1NewSizePercent
>>>>>     G1DefaultMaxNewGenPercent is being replaced by
>>>>>     G1MaxNewSizePercent
>>>>>     G1OldCSetRegionLiveThresholdPercent is being replaced by
>>>>>     G1MixedGCLiveThresholdPercent
>>>>>
>>>>>     Thanks,
>>>>>
>>>>>     JohnC
>>>>
>>>
>>>
>>
>

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