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Re: [Xen-devel] Strange interdependace between domains

  • To: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
  • From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
  • Date: Fri, 21 Feb 2014 07:31:05 +0100
  • Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Don Slutz <dslutz@xxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxx, Simon Martin <furryfuttock@xxxxxxxxx>, Nate Studer <nate.studer@xxxxxxxxxxxxxxx>
  • Delivery-date: Fri, 21 Feb 2014 06:31:28 +0000
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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 Gross                 Principal Developer Operating Systems
PBG PDG ES&S SWE OS6                   Telephone: +49 (0) 89 62060 2932
Fujitsu                                   e-mail: juergen.gross@xxxxxxxxxxxxxx
Mies-van-der-Rohe-Str. 8                Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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