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 `. `'`
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