Re: RAM utilization issues

[Avi Kivity <avi@redhat.com>]

On 01/12/2012 11:27 AM, Jonathan Petersson wrote:
> Hi,
>
> Throughout the last few months we've been slowly migrating off our old
> VMware installation to KVM, most of it has been successful and people
> has been happy with the end-result.
>
> The new infrastructure obviously has a bit more of power which is
> heavily utilized by the guests however compared to VMware the RAM
> usage is way above what we've expected.
>
> In our VMware environment we operated at 24GB with ballooning and we
> were able to maintain usage at around 90% without any swapping.
> However with the new environment we've 24x3 GB och RAM and we're
> seeing a 80% utilization across the board with the same amount of
> guests.
>
> Please notice that we've both ballooning (on both the host and guest)
> and KSM enabled, hugepages hasn't made any major difference so we've
> chosen to disable this. If you've any input as to why we're seeing
> this behavior or if it's expected we'd appreciate it. In addition to
> this we're utilizing virtio_blk/net/pci/ring and vhost_net.
>
> Some data:
> root@kvm01-01:~# grep -i balloon /boot/config-$(uname -r)
> CONFIG_VMWARE_BALLOON=m
> CONFIG_XEN_BALLOON=y
> CONFIG_VIRTIO_BALLOON=y
>

What's the aggregate size of the guests (sum of all guest memory
sizes)?  How many guests?  Are you in fact using the balloon?  How?

-- 
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