Re: [Xen-devel] "cpus" config parameter broken?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 10/1/08 18:38, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> As a logical consequence:
> 
> - the v->cpu_affinity mask should never have bits set for
>   processors that don't exist on the current physical system
>   (although all bits set == "any" is probably an OK exception)

This is already the case.

> - the modulo behavior currently implemented in "xm vcpu-pin"
>   and the config file "cpus" parameter should be removed, and

Possibly.

> - if cpu values are specified by "xm vcpu-pin" or "cpus"
>   beyond the number of physical cpus, the xm command should
>   fail.

Again, possibly. I don't see much wrong with a liberal interpretation of
otherwise incorrect cpu config parameters though. If we tighten things up
then we need to make it easier to access CPU topology info from within
domain config files.

 -- Keir

> Agreed?
> 
>> -----Original Message-----
>> From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>> Sent: Wednesday, January 09, 2008 12:17 PM
>> To: dan.magenheimer@xxxxxxxxxx; Ian Pratt;
>> xen-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: Re: [Xen-devel] "cpus" config parameter broken?
>> 
>> 
>> On 9/1/08 18:40, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:
>> 
>>> My opinion: CPU affinity/restriction should NOT be preserved
>>> across migration.  Or if it is, it should only be preserved
>>> when the source and target have the same number of pcpus
>>> (thus allowing save/restore to work OK).  Or maybe it should
>>> only be preserved for save/restore and not for migration.
>>>>>>>>>>>> Comments? <<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>> 
>> I agree with that. Unless save/restore is on the same machine
>> (identified in
>> some way) or at least has identical CPU topology as far as we can see.
>> Otherwise some higher-level entity needs to be smart enough
>> to work out
>> affinity during restore and issue the correct 'xm' commands
>> (or equivalent).
>> 
>>  -- Keir
>> 
>> 
>> 
> 



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