On Tue, Jun 26, 2012 at 1:40 PM, Rik van Riel <riel@xxxxxxxxxx> wrote: > On 06/26/2012 04:32 PM, Frank Swiderski wrote: >> >> This implementation of a virtio balloon driver uses the page cache to >> "store" pages that have been released to the host. The communication >> (outside of target counts) is one way--the guest notifies the host when >> it adds a page to the page cache, allowing the host to madvise(2) with >> MADV_DONTNEED. Reclaim in the guest is therefore automatic and implicit >> (via the regular page reclaim). This means that inflating the balloon >> is similar to the existing balloon mechanism, but the deflate is >> different--it re-uses existing Linux kernel functionality to >> automatically reclaim. >> >> Signed-off-by: Frank Swiderski<fes@xxxxxxxxxx> > > > It is a great idea, but how can this memory balancing > possibly work if someone uses memory cgroups inside a > guest? Thanks and good point--this isn't something that I considered in the implementation. > Having said that, we currently do not have proper > memory reclaim balancing between cgroups at all, so > requiring that of this balloon driver would be > unreasonable. > > The code looks good to me, my only worry is the > code duplication. We now have 5 balloon drivers, > for 4 hypervisors, all implementing everything > from scratch... Do you have any recommendations on this? I could (I think reasonably so) modify the existing virtio_balloon.c and have it change behavior based on a feature bit or other configuration. I'm not sure that really addresses the root of what you're pointing out--it's still adding a different implementation, but doing so as an extension of an existing one. fes _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
