Re: x86/dom0: limit dom0_max_vcpus value

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 12/03/12 16:12, Jan Beulich wrote:
>>>> On 12.03.12 at 16:56, Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>> This caused particularly poor performance when booting a server in
>> uniprocessor mode for debugging reasons, and had 4 dom0 vcpus competing
>> for 1pcpus worth of time.
> NAK. This was intentionally removed in an earlier c/s (and I'm in fact
> making use of this for certain types of stress tests). No-one forces
> you or anyone else to boot with dom0_max_vcpus=4 when there's
> just a single pCPU.
>
> Jan

What is the justification for removing it? c/s 18266:d31546a3883e has no
explanation.

This is now resulting in a command line parameter with "max" in its name
acting unlike all other "max" parameters.  There is certainly an
argument for introducing a "dom0_cpus" parameter for setting an exact
number, but I feel that this behavior is wrong for a parameter with
"max" in its name.

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com