cboxes on NehalemEX

cboxes on NehalemEX

[Animesh K Trivedi1]

Hi all,

I'm testing/using uncore support on a dual socket NehalemEX (Xeon E7520)
box on 3.7-rc1.
It shows me only 4 CBOXes under devices. Although the document (Uncore
programming
for 7500) says that there should be 8 CBOXes. Am I missing something?

Also, I have a dual socket configuration, in which I assume each processor
has its own set of
CBOXes. How are number of CBOXes related to number of physical processors?
In order to
get a global view of LLC behaviour shouldn't I have to sum up the count of
events from all
physical processor's CBOXes.

Thanks,
--
Animesh

Re: cboxes on NehalemEX

[Andi Kleen]

Animesh K Trivedi1 <ZRLATR@ch.ibm.com> writes:

> Hi all,
>
> I'm testing/using uncore support on a dual socket NehalemEX (Xeon E7520)
> box on 3.7-rc1.
> It shows me only 4 CBOXes under devices. Although the document (Uncore
> programming
> for 7500) says that there should be 8 CBOXes. Am I missing something?

The number of CBOXes depends on the number of CPU cores in the socket.
Each core has a CBOX.  You would only see 8 on a 8 core CPU.


> get a global view of LLC behaviour shouldn't I have to sum up the count of
> events from all
> physical processor's CBOXes.

Yes. Each BOX has its own counters.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only

Re: cboxes on NehalemEX

[Animesh K Trivedi1]

Hi Andi,

Thanks for the reply. E7520 have 4 cores (and 8 threads, though I assume
that is irrelevant) but in a dual-socket configuration shouldn't I see
total of 8 CBoxes? 4 CBoxes for each E7520 processor ?

Cheers,
--
Animesh

Andi Kleen <andi@firstfloor.org> wrote on 11/28/2012 09:33:22 PM:

> From: Andi Kleen <andi@firstfloor.org>
> To: Animesh K Trivedi1/Zurich/IBM@IBMCH,
> Cc: linux-perf-users@vger.kernel.org, Bernard Metzler
<BMT@zurich.ibm.com>
> Date: 11/28/2012 09:33 PM
> Subject: Re: cboxes on NehalemEX
>
> Animesh K Trivedi1 <ZRLATR@ch.ibm.com> writes:
>
> > Hi all,
> >
> > I'm testing/using uncore support on a dual socket NehalemEX (Xeon
E7520)
> > box on 3.7-rc1.
> > It shows me only 4 CBOXes under devices. Although the document (Uncore
> > programming
> > for 7500) says that there should be 8 CBOXes. Am I missing something?
>
> The number of CBOXes depends on the number of CPU cores in the socket.
> Each core has a CBOX.  You would only see 8 on a 8 core CPU.
>
>
> > get a global view of LLC behaviour shouldn't I have to sum up the count
of
> > events from all
> > physical processor's CBOXes.
>
> Yes. Each BOX has its own counters.
>
> -Andi
>
> --
> ak@linux.intel.com -- Speaking for myself only
>