メモリ使用量

余分に使用されるメモリの量
from(to) = NewSize / (1 + 1 + SurvivorRatio)

例

 -Xms2560m -Xmx2560m -XX:NewSize=768m -XX:MaxNewSize=768M -XX:SurvivorRatio=8

768m / (1 + 1 + 8) = 77m

eden     616m
from(to) 77m 

[ParNew 655720K->141587K(2542848K), 0.5363089 secs]
Heap after gc invocations=2:
 par new generation   total 707840K, used 78592K [0xfffffd7f52a00000, 0xfffffd7f82a00000,
0xfffffd7f82a00000)
  eden space 629248K,   0% used [0xfffffd7f52a00000, 0xfffffd7f52a00000, 0xfffffd7f7908000
0)
  from space 78592K, 100% used [0xfffffd7f79080000, 0xfffffd7f7dd40000, 0xfffffd7f7dd40000
)
  to   space 78592K,   0% used [0xfffffd7f7dd40000, 0xfffffd7f7dd40000, 0xfffffd7f82a00000
)
 concurrent mark-sweep generation total 1835008K, used 62995K [0xfffffd7f82a00000, 0xfffff
d7ff2a00000, 0xfffffd7ff2a00000)
 concurrent-mark-sweep perm gen total 21248K, used 15604K [0xfffffd7ff2a00000, 0xfffffd7ff
3ec0000, 0xfffffd7ff7e00000)
}

 -Xms2560m -Xmx2560m -XX:NewSize=1024m -XX:MaxNewSize=1024M -XX:SurvivorRatio=2

1024m / (1 + 1 + 2) = 256m

eden     512m
from(to) 256m

[ParNew 949894K->440607K(2359296K), 0.8114740 secs]
Heap after gc invocations=21:
 par new generation   total 786432K, used 248896K [0xfffffd7f52a00000, 0xfffffd7f92a00000,
 0xfffffd7f92a00000)
  eden space 524288K,   0% used [0xfffffd7f52a00000, 0xfffffd7f52a00000, 0xfffffd7f72a0000
0)
  from space 262144K,  94% used [0xfffffd7f82a00000, 0xfffffd7f91d10078, 0xfffffd7f92a0000
0)
  to   space 262144K,   0% used [0xfffffd7f72a00000, 0xfffffd7f72a00000, 0xfffffd7f82a0000
0)
 concurrent mark-sweep generation total 1572864K, used 191711K [0xfffffd7f92a00000, 0xffff
fd7ff2a00000, 0xfffffd7ff2a00000)
 concurrent-mark-sweep perm gen total 21248K, used 18220K [0xfffffd7ff2a00000, 0xfffffd7ff
3ec0000, 0xfffffd7ff7e00000)
}