UseAdaptiveGCBoundary?
Jon Masamitsu
jon.masamitsu at oracle.com
Thu Feb 9 14:39:22 UTC 2012
Ramki,
I cannot say that I would recommend it's use. The problem with
UseAdaptiveGCBoundary
is all in the policy that it uses to decide how to move the boundary.
It used to sometimes
back itself into a corner (young gen size and old gen size which was sub
optimal)
and not be able to get itself out. I think that can still be a problem
but perhaps the
bigger problem is that the policy thinks that it is optimal to divide
the the GC times
evenly between the young GC's and old GC's and that is not always the
case. In
general that policy produces reasonably good results but when that
policy can
drive the moving of the boundary, I've seen cases where there are
performance
regressions (i.e., GC ergonomics turned on but worse performance when the
boundary moving is additionally turned on).
Jon
On 2/7/2012 9:04 AM, Srinivas Ramakrishna wrote:
> Hi Jon, John, et al. --
>
> What's the current status of and experience with UseAdaptiveGCBoundary?
> As I recall a (long) while ago there was some performance issue with it,
> although
> I can't recall the specific details.
> Is this flag something you recommend trying out? Are there performance
> sharp-corners that one should watch out for if one were to enable this
> feature ?
>
> thanks for any tips!
> -- ramki
>
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