Re: Strange interdependace between domains

[Juergen Gross <juergen.gross@ts.fujitsu.com>]

On 20.02.2014 19:22, Dario Faggioli wrote:
> On gio, 2014-02-20 at 07:07 +0100, Juergen Gross wrote:
>> On 18.02.2014 19:06, Dario Faggioli wrote:
>
>>> While this one, although a bit more "boring" than the above, would
>>> probably be something quite valuable to have!
>>>
>>> I can only think of rather expensive ways of implementing it, involving
>>> going through all the cpupools and, for each cpupool, through all its
>>> cpus and check the topology relationships, but perhaps there are others
>>> (I'll think harder).
>>>
>> Adding some information like this would be nice, indeed. But I think we should
>> not limit this to just hyperthreads. There are more levels of shared resources,
>> like caches or memory interfaces on the same socket. In case we want to add
>> information about potential performance influences due to shared resources, we
>> should be more generic.
>>
> All true... To the point that I know also wonder what a suitable
> interface and a not too verbose output configuration could be...

Well, looking at the available topology information I think it should look like
the following example:

# xl cpupool-list --shareinfo
Name          CPUs   Sched     Active  Domain count  shared resources
Pool-0          1    credit       y         1        core:   lw_pool
lw_pool         1    credit       y         0        core:   Pool-0
bs2_pool        2    credit       y         1        socket: Pool-0,lw_pool

What do you think?

>> And what about some NUMA information? Wouldn't it be worthwhile to show memory
>> locality information as well? This should be considered to be displayed by
>> "xl list", too.
>>
> Indeed. I actually have an half backed series doing right that. It's a
> bit more complicated (still from an interface point of view), as that
> info resides in Xen, and some new hcall or similar is required to
> retrieve that.
>
> I'll post it in early 4.5 dev cycle.

Please do!


Juergen

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Juergen Gross                 Principal Developer Operating Systems
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