Xen users - Nov 2005 - Sun and BEA 1.5 64-bit JVMs not happy w/ Xen on x86_64

I''m running a SLES9 DomU, with Xen3 changeset 7608.

Both BEA''s JRockit 25.2.0-jdk1.5.0_03-linux-x64 and Sun''s 
jdk-1_5_0_05-linux-amd64 fail, receiving ENOMEM when trying to 
anonymously mmap memory to use [after a number of successful 
allocations]. This happens even when running something as simple as 
"java -version". The DomU in question has 1GB RAM and 4GB swap
available
for its use and is running no substantial other processes.

This issue does not occur when running 32-bit JVMs, even within the 
exact same 64-bit DomU.


If there''s anything I can do to better narrow down the issue, please
let
me know.


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> I''m running a SLES9 DomU, with Xen3 changeset 7608.
> 
> Both BEA''s JRockit 25.2.0-jdk1.5.0_03-linux-x64 and Sun''s
> jdk-1_5_0_05-linux-amd64 fail, receiving ENOMEM when trying 
> to anonymously mmap memory to use [after a number of 
> successful allocations]. This happens even when running 
> something as simple as "java -version". The DomU in question 
> has 1GB RAM and 4GB swap available for its use and is running 
> no substantial other processes.
> 
> This issue does not occur when running 32-bit JVMs, even 
> within the exact same 64-bit DomU.
Please can you give us a recipe for provoking the bug using the sun jvm
(or better, a little program that just does the mmap).

[or are you saying that just running ''jave -version'' a bunch
of times
causes the issue? ]

When the machine is in the sick state, the output of ''free'',
''ps auxw''
an ''cat /proc/slabinfo'' may be useful.

Thanks,
Ian

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Ian Pratt wrote:
> Please can you give us a recipe for provoking the bug using the sun jvm
> (or better, a little program that just does the mmap).
>
> [or are you saying that just running ''jave -version'' a
bunch of times
> causes the issue? ]
>   
Running "java -version" causes the issue every time, starting 
immediately after boot.

I just strace''d the Sun JVM, and it appears that the only mmap failing 
is requesting a full 1GB of RAM, and that only inconsequential amounts 
have been allocated hitherto. Looking into this further, I''ve found 
evidence that there''s a bug in Sun''s 64-bit JVMs causing them
to
allocate much more memory than is needed:
http://forum.java.sun.com/thread.jspa?threadID=651637

...and, further, that "ulimit -v" isn''t being set
appropriately on this
system on account of an administration bug. [Swap was enabled only 
*after* boot, whereas SLES calculates the default ulimit -v as a 
percentage of total ram+swap at boot time].

Oops; sorry for the noise.

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