-XX:NewRatio

from: https://blog.codecentric.de/en/2012/08/useful-jvm-flags-part-5-young-generation-garbage-collection/

-XX:NewRatio

It is also possible to specify the young generation size in relation to the size of the old generation. The potential advantage of this approach is that the young generation will grow and shrink automatically when the JVM dynamically adjusts the total heap size at run time. The flag -XX:NewRatio allows us to specify the factor by which the old generation should be larger than the young generation. For example, with -XX:NewRatio=3 the old generation will be three times as large as the young generation. That is, the old generation will occupy 3/4 and the young generation will occupy 1/4 of the heap.
If we mix absolute and relative sizing of the young generation, the absolute values always have precedence. Consider the following example:

$ java -XX:NewSize=32m -XX:MaxNewSize=512m -XX:NewRatio=3 MyApp

With these settings, the JVM will try to size the young generation at one third of the old generation size, but it will never let young generation size fall below 32 MB or exceed 512 MB.
There is no general rule if absolute or relative young generation sizing is preferable. If we know the memory usage of our application well, it can be advantageous to specify a fixed size both for the total heap and the young generation, and it can also be useful to specify a ratio. If we only know a little or maybe nothing at all about our application in this respect, the correct approach is to just let the JVM do the work and not to mess around with the flags. If the application runs smoothly, we can be happy that we didn’t put in extra effort where none was needed. And should we encounter performance problems or OutOfMemoryErrors, we would still need to first perform a series of meaningful measurements to narrow down the root cause of the problem before moving on to tuning.