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

Bengt Rutisson bengt.rutisson at oracle.com
Fri Dec 21 05:47:32 PST 2012


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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