control: reassign -1 src:linux On Tue, May 24, 2016 at 02:52:22PM +0000, Anna Melekhova (Vorobyova) wrote: > Package: kernel kernel is very much not an available debian package name > Version: Debian 7, Debian 8 and those are not valid versions.. Anyway, just reassigning to linux without setting a version. > There is QEMU/KVM and a Debian Linux running inside the guest. The amount > of memory available for guest could be adjusted by balloon for better > host scalability. The problem that this change is visible for end-user > actually using the guest. This could (potentially) result in lawsuite > from the end-user to hosting provides. > > Though there is a problem in this setup. The end-user and hosting provider > have signed SLA agreement in which some amount of memory is guaranted for > the guest. The good thing is that this memory will be given to the guest > when the guest will really need it (f.e. with OOM in guest and with > VIRTIO_BALLOON_F_DEFLATE_ON_OOM configuration flag set). The bad thing > is that end-user does not know this. > > Balloon by default reduce the amount of memory exposed to the end-user > each time when the page is stolen from guest or returned back by using > adjust_managed_page_count and thus /proc/meminfo shows reduced amount > of memory. > > Steps to Reproduce: > 1. inflate guest balloon > 2. amount of memory in /proc/meminfo in reduced in guest > > Expected results: > no changes in /proc/meminfo in guest if properly configured in host > > The problem is addressed in mainstream Linux with the following patchset: > > commit 997e120843e82609c8d99a9d5714e6cf91e14cbe > Author: Denis V. Lunev <den@openvz.org> > Date: Thu Aug 20 00:49:49 2015 +0300 > virtio_balloon: do not change memory amount visible via /proc/meminfo > > Balloon device is frequently used as a mean of cooperative memory control > in between guest and host to manage memory overcommitment. This is the > typical case for any hosting workload when KVM guest is provided for > end-user. > > Though there is a problem in this setup. The end-user and hosting provider > have signed SLA agreement in which some amount of memory is guaranted for > the guest. The good thing is that this memory will be given to the guest > when the guest will really need it (f.e. with OOM in guest and with > VIRTIO_BALLOON_F_DEFLATE_ON_OOM configuration flag set). The bad thing > is that end-user does not know this. > > Balloon by default reduce the amount of memory exposed to the end-user > each time when the page is stolen from guest or returned back by using > adjust_managed_page_count and thus /proc/meminfo shows reduced amount > of memory. > > Fortunately the solution is simple, we should just avoid to call > adjust_managed_page_count with VIRTIO_BALLOON_F_DEFLATE_ON_OOM set. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > > commit b4d34037329f46ed818d3b0a6e1e23b9c8721f79 > Author: Denis V. Lunev <den@openvz.org> > Date: Thu Aug 20 00:49:48 2015 +0300 > virtio_ballon: change stub of release_pages_by_pfn > > and rename it to release_pages_balloon. The function originally takes > arrays of pfns and now it takes pointer to struct virtio_ballon. > This change is necessary to conditionally call adjust_managed_page_count > in the next patch. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> -- regards, Mattia Rizzolo GPG Key: 66AE 2B4A FCCF 3F52 DA18 4D18 4B04 3FCD B944 4540 .''`. more about me: https://mapreri.org : :' : Launchpad user: https://launchpad.net/~mapreri `. `'` Debian QA page: https://qa.debian.org/developer.php?login=mattia `-
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