Re: [XenPPC] Out of memory issues with xen

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Fri, 2006-08-25 at 14:18 -0400, Maria Butrico wrote:
> I should report to the list some of issues we have been having with 
> memory when using xen, it's dom0 and another partition. 
> 
> The first problem is that by default dom0 only has 64M and that there is 
> no way to change this other that changing xen (the fix is easy enough).  
> 64M is too little to run the compiler and build the tools. 

You don't need to run a compiler in dom0. I don't...

> The second problem is that when we change xen to give dom0 128M dom0 we 
> do not have enough memory to make another partition even though the 
> machine has 512M.  This is a bug that Jimi is currently looking into (I 
> think).

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=744

It's assigned to me.

> So the current state of things for us developing an OS on xen is that we 
> boot with 128M, build and save the tools, then re-boot with 64M and run 
> the OS.  Of course, we do not have to rebuild the tools all the time 
> while we rebuild the OS quite a few times. 
> 
> There is an effort, related to our larger project, to use an nfsroot for 
> xen.  This almost works, but in 64M run out of memory quickly.  There 
> being no paging space with this configuration when the kernel has no 
> more space it crashes. 
> 
> Ideally we would like at least 128M on dom0 and the ability to make 
> another partition of 64M or 128M. 

I have a largish patch that I hope to check in soon that will allow the
management tools to specify the RMA size. Right now Xen allocates a 64MB
RMA without the knowledge of the tools, so then the tools try to
increase the size beyond that.

Setting dom0 size via a boot argument (and maybe defaulting to >64MB)
will follow from that later.

-- 
Hollis Blanchard
IBM Linux Technology Center


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