[pve-devel] applied: [PATCH V2 qemu-server 0/2] enable balloon free-page-reporting

[Thomas Lamprecht]

On 06.03.22 13:46, Alexandre Derumier wrote:
> Hi,
> 
> Currently, if a guest vm allocate a memory page, and freed it later in the guest,
> the memory is not freed on the host side.
> 
> Balloon device have a new option since qemu 5.1 "free-page-reporting" (and need host kernel 5.7)
> 
> https://events19.linuxfoundation.org/wp-content/uploads/2017/12/KVMForum2018.pdf
> https://lwn.net/Articles/759413/
> 
> This is working like the discard option for disk, memory is freed async by the host when vm is freeing it.
> 
> I'm running it production since 1 month without any problem. With a lot of vms and spiky workload, the memory
> freed is really huge.
> 
> Here an example of a host with 650GB+200GB ksm going down to 250GB memory
> https://mutulin1.odiso.net/ballon-size.png
> (around 400vms with 2GB max memory, previously always allocated)
> 
> 
> This patch enabled it by default force machine version >= 6.2.
> 
> 
> changelogv2:
> 
> - enabled it only for machine version > 6.2
> - add test
> 
> Alexandre Derumier (2):
>   enable balloon free-page-reporting
>   add test for virtio-balloon free-page-reporting=on. (qemu 6.2)
> 
>  PVE/QemuServer.pm                             |  4 ++-
>  test/cfg2cmd/q35-simple-7.0.conf.cmd          |  2 +-
>  .../simple-balloon-free-page-reporting.conf   | 15 +++++++++
>  ...imple-balloon-free-page-reporting.conf.cmd | 33 +++++++++++++++++++
>  4 files changed, 52 insertions(+), 2 deletions(-)
>  create mode 100644 test/cfg2cmd/simple-balloon-free-page-reporting.conf
>  create mode 100644 test/cfg2cmd/simple-balloon-free-page-reporting.conf.cmd
> 



applied series, thanks! Had to fixup the existing un-versioned tests though.