Re: [Engine-devel] Fixed -Xmx could kill your JVM
On Wednesday 12 September 2012 06:36 PM, Alon Bar-Lev wrote:
----- Original Message -----
> From: "Juan Hernandez" <jhernand(a)redhat.com>
> To: "Laszlo Hornyak" <lhornyak(a)redhat.com>
> Cc: engine-devel(a)ovirt.org
> Sent: Wednesday, September 12, 2012 3:57:33 PM
> Subject: Re: [Engine-devel] Fixed -Xmx could kill your JVM
<snip>
>
> Worst case we can change the defaults for ENGINE_HEAP_MIN and
> ENGINE_HEAP_MAX to get that behavior, for example:
>
> ENGINE_HEAP_MIN=128m
> ENGINE_HEAP_MAX=1g
>
> I am open to do that change, specially if you show me hard data
> proving
> that it is better for performance ;-) .
We are talking about virtual memory, allocation of the heap is done as reserved, so there
is no real impact on the system if memory is unused. When a reserved page is actually used
it is committed.
Unless there is a system with small page file, there is no real reason to use lower
values in HEAP_MIN.
Alon.
I've seen that Java experts from Sun (now Oracle) recommend to identify
a good (high enough) value for the heap size and set the same value for
both min and max, during the sessions on Java performance in the Java
One conference.
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