[xenpreview-dev] default dom0 memory size comsumes almost all memory available on system

[Krysan, Susan]

I would like to start a discussion concerning the default memory size allocated to dom0 in the version of Xen bundled with SLES10.  I do not specify a dom0 memory size in /boot/grub/menu.lst, nor do I set a size using xm mem-set or xm max-mem.  No matter what amount of memory is available on the box, dom0 is allocated almost all of the memory by default.  For example, on an 8 GB box, only about 132 MB is left free for booting domUs.  This surprised me.  In an enterprise server environment, it is most likely that users will be using Xen either to boot many small memory size domUs or even just one or two larger ones.  With only 132 MB available on an 8 GB system, this means that a user would get insufficient memory errors when trying to boot domUs if he did not remember to configure the size of dom0.  Wouldn't it be more user friendly to have a default memory size for dom0 which is smaller but large enough for dom0 to run efficiently, perhaps 512 MB, and allow most of the memory on the box to be free for booting domUs, since the purpose of booting Xen is to run domUs?

Thanks,

Sue Krysan
Linux Systems Group
Unisys Corporation