This is being taken up on hotspot-runtime-dev, but I wanted to make a
couple of responses to Alan ...
On 6/06/2012 12:43 AM, Alan Bateman wrote:
I would suggest moving the thread to hotspot-dev or hotspot-runtime-dev.
On attempting to use -XX:MaxDirectMemorySize=5g on a 32-bit system then
ideally this should be a fatal error, I don't think we would truncate
Presently hotspot does, simply because a 64-bit value is assigned to a
32-bit variable. Other than that hotspot doesn't even look at the value
of this flag. We would have to change that to sanity check its range.
the value to 32-bit. On specifying a value of -1 then I would suggest it
should be consistent to other others, for example -XX:MaxHeapSize=-1
will fail with an unrecognized VM option error.
A value of -1 means "use the default". The JDK side defines what that
default is. Hotspots uses -1 a fair bit like this, when the actual
default comes from outside the VM (eg OS defaults, or in this case
something determined on the JDK side). We could instead not define the
property at all as a way to say "use the default" - but that would then
need a change on the JDK side and we would have issues with JDK version
in that case. But it may be we can use -1 internally yet reject the user
setting -1 directly.
Please follow up on [email protected].
David
-Alan.
