On 7 July 2010 00:02, Thor Lancelot Simon <t...@panix.com> wrote: > On Tue, Jul 06, 2010 at 10:56:22PM +0530, Cherry G. Mathew wrote: >> >> Briefly, there are two methods to play with this now. >> >> >From dom0: >> >> # xm mem-set $domid $newmemsz >> >> or, from within the domU >> >> # sysctl -w kern.xen.balloon.target=$newtargetinpages > > How does one control, from the dom0, how much memory a domU may use? >
Hi Thor, use 'xm mem-set' command as mentioned above. # xm mem-set $domid $newmemsz The driver tries to honour this (asynchronously - there's a kernel thread which polls for these requests) within reasonable limits defined by: - domU memory pressure ( ie;, UVM can't hand out any more wired frames == balloon driver gives up after BALLOON_RETRIES) - Absolute minimum and maximum, defined as XEN_RESERVATION_ and XEN_RESERVATION_MAX in the source. These values definitely need more tweaking ( for eg: its perfectly possible to panic()/DOS a domU by over-expanding the balloon. The min limit needs to co-operate with UVM to prevent this from happening. I hope this helps, -- ~Cherry
