RE: [Xen-devel] DOM0 memory allocation - Ian Pratt - com.xensource.lists.xen-devel

2 messages in com.xensource.lists.xen-develRE: [Xen-devel] DOM0 memory allocation

From	Sent On	Attachments
Keir Fraser	25 Feb 2005 10:40
Ian Pratt	26 Feb 2005 10:47

Subject:	RE: [Xen-devel] DOM0 memory allocation
From:	Ian Pratt (m+Ia...@cl.cam.ac.uk)
Date:	02/26/2005 10:47:30 AM
List:	com.xensource.lists.xen-devel

In the unstable tree the default memory allocation for DOM0 is now *all* available memory (rather than the somewhat underwhelming previous default of 16MB).

This ought to be a much more useful default, but you must remember to 'balloon down' DOM0's memory reservation before creating new domains! The interface file is /proc/xen/balloon.

As well as the allocation for the domain, make sure you give Xen some slack to play with when you begin starting domains. Xen's per-domain memory requirements are normally very small (32KB), but when you start a live-migration of a domain Xen will need memory to store shadow page tables for the duration of the migration.

We really need to update the tools to autmoatically balloon down domain 0 and leave some approprite slack for Xen (e.g. maybe 16MB total for the system by default). Volunteers?

We also need to audit Xen's out of memory paths to make sure they're handled appropriately. (The forthcoming shadow mode checkin should handle that path rather better).

Ian