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

John Cuthbertson john.cuthbertson at oracle.com
Thu Dec 20 18:04:23 UTC 2012

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.



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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