[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] Re: [Xen-users] (xen) Possible bug: Memory squeeze in netback driver.

On 7 Jun 2006, at 21:43, Anthony Liguori wrote:

I suspected it would but I was hoping it wouldn't. Do this mean that the netback driver needs to be able to increase it's reservation? If so, should we be enforcing (in the tools) that memory < maxmem? Any thoughts Keir?

The kernel should be able to do it for itself. Drivers inform how much 'headroom' they need via balloon_update_driver_allowance(). Balloon driver then strives to keep its memory allocation below maxmem by that amount. Possibly the balloon driver needs a kick when allocation fails in teh driver, to expand the balloon a little. Another alternative is for drivers to incr/decr reservation via another balloon driver interface, giving another hook point for the balloon driver to do something sensible.

So, in short, tools may be able to screw things for a short while (and maybe crash things entirely, if maxmem is reduced drastically with no prior warning (update of memory target)). But the balloon driver is expected to recover except in that kind of unreasonable circumstance.

 -- Keir

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.