0006893: xen_balloon errors in syslog

Notes
(0018820) JohnnyHughes (administrator) 2014-01-10 12:58	This from David Vrabel on the mail list: Drivers (e.g., blkback) use ballooned pages for use for foreign mappings. Depending on dom0_mem options there may be no ballooned memory available at boot and dom0's balloon is increased by allocating pages. This decreases current_kb. The balloon driver then tries to decrease the balloon to match the target but it can only do this by hotplugging new memory. A bug in the balloon driver means the location of this memory overlaps with an address range that is already in use and the hotplug will fail. As a workaround you can boot dom0 with a suitable amount of pre-ballooned memory with: dom0_mem=3G,max:4G You may need to experiment with the max: value.

(0018821) JohnnyHughes (administrator) 2014-01-10 12:59	I would suggest that approx. 16 MB per VM is a reasonable amount of pre-ballooned memory. e.g., dom0_mem=3G,max:4G would allow for approx. 64 VMs.

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