G1gc compaction algorithm

[Yu Zhang]

It will first add old regions if the estimated time is under the 
MaxGCPauseMilli.  If the estimated time is higher than  MaxGCPauseMilli, 
it will add the minimum decided by 
#candidate-regions/MixedGCCountTarget.  If you set MixedGCCountTarget 
too high, the minimum will be too low.  In your case, it is 2.

Thanks,
Jenny

On 7/16/2014 6:46 PM, Martin Makundi wrote:
>
>     2. For most of the time, eden size is 1.4g, survivor 150m, the
>     rest is old gen.  I am not sure how much of the old gen is used
>     for humongous allocations.  But it seems there are some tunings
>     you can try to help mixed gc:
>       - old regions added to cset is 2-14 for mixed gc.  Most of the
>     time the reason is 'predicted time too high'.  You can try either
>     increase -XX:MaxGCPauseMillis to a higher value, or decrease
>     -XX:G1MixedGCCountTarget (currently it is 80) so that more old
>     regions can be added.
>
>
> Does it attempt to do any mixed gc if it cannot do 
> all G1MixedGCCountTarget or is the value G1MixedGCCountTarget just an 
> upper limit? If it just is an upper limit we could keep it at 80 or 
> higher?

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