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From "Rana Dasgupta" <rdasg...@gmail.com>
Subject Re: [drlvm]Leave classunloading on by default?
Date Tue, 20 Nov 2007 17:35:07 GMT
Hi Aleksey,
   No we cannot turn on force_major_collect=true, you are right. Only turn
on ignore_vtable_tracing to be true by default. The force_major_collect=true
is not needed for CU, only for testing. Unloading happens when major
collections happen naturally due to heap conditions and is not caused by
class unloading. So there should be no difference. The overhead of vtable
tracing is small.


On 11/20/07, Aleksey Shipilev <aleksey.shipilev@gmail.com> wrote:

> Hi, Rana!
> On Sep 24, 2007 12:11 AM, Rana Dasgupta <rdasgupt@gmail.com> wrote:
> > Harmony DRLVM has recently added a class unloading feature. It's now
> > ready for trial and regular use. It's not on by default, and to turn
> > on the feature, a couple of options are needed:
> >  -XX:gc.ignore_vtable_tracing=false  -XX:gc.force_major_collect=true
> AFAIU, forcing major collect will disable minor collection entirely,
> so we will have the major collection every time the heap is full. If
> my understanding is correct, then GC pauses will be significantly
> larger thus degrading workload performance. Have you counted
> minor/major collection ratios for CU on/off?
> Thanks,
> Aleksey.

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