Re: different maximum Java -Xmx on kernel 2.6.9 (RedHat 4 update 2) and 2.6.22 (CentOS 5.2)

Hi Robert,

Thanks for your reply!

What does the command 'free' show?  It is entirely possible that the 878
meg of ram has gotten 'eaten' by additional processes.

# free
total used free shared
buffers cached
Mem: 4074980 161636 3913344 0 13740
117696
-/+ buffers/cache: 30200 4044780
Swap: 2031608 0 2031608


So it seems to me that there should be enough memory available for
java -Xmx3500m.


Another possiblity is that you didn't install the PAE kernel -- eg I am
not sure if the default CentOS 5.2 32bit installed installs the PAE
kernel by default.  Without the PAE, you might not be able to allocate
all (or nearly all) of the 4gig to any one process. Or to even allocate
all of the 4gig RAM at all.

Initially CentOS 5.2 did install a PAE kernel, but since this didn't
work I decided to install the kernel SRPM and recompile it with
several different option to see if it makes a difference. However,
playing with the HIGHMEM options (4G, 64G, etc) did not help. At the
moment I am back using the default PAE kernel (the output of free
above is with the PAE kernel).

Any other ideas?

Thanks!
.

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