[libvirt] [PATCH] docs: update docs for cpu_shares setting

[Eric Blake]

On 01/29/2011 10:43 PM, Osier Yang wrote:
> * tools/virsh.pod
> ---
>  tools/virsh.pod |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/tools/virsh.pod b/tools/virsh.pod
> index 441ca8a..d3262b6 100644
> --- a/tools/virsh.pod
> +++ b/tools/virsh.pod
> @@ -566,7 +566,11 @@ Xen (credit scheduler): weight, cap
> 
>  ESX (allocation scheduler): reservation, limit, shares
> 
> -B<Note>: The cpu_shares parameter has a valid value range of 0-262144.
> +B<Note>: The cpu_shares parameter has a valid value range of 0-262144, however,
> +negative number and positive number greater than 262144 are allowed, but
> +negative number will be converted into positive number, and positive number
> +greater than 262144 will be reduced to 262144 by cgroup in the end, e.g. -1
> +can be used as useful shorthand for 262144.

The range of 262144 is specific to cgroups (qemu and lxc); it is
possible that some other hypervisor may add similar support for this
parameter, but have a different range.  Then again, we already
documented it is specific to qemu and lxc, so we could update a change
in range at the time of introducing the cpu_shares parameter to another
hypervisor.

However, your attempt is still wordy.  Can we go with something more
compact, as in:

B<Note>: The cpu_shares parameter has a valid value range of 0-262144;
negative values are wrapped to positive, and larger values are capped at
the maximum.  Therefore, -1 is a useful shorthand for 262144.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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