From: Andi Kleen <andi@firstfloor.org>
To: Chris Freehill <cfreehill@utexas.edu>
Cc: Andi Kleen <andi@firstfloor.org>, linux-perf-users@vger.kernel.org
Subject: Re: perf uncore behavior
Date: Sat, 2 May 2015 14:16:11 +0200 [thread overview]
Message-ID: <20150502121611.GK2366@two.firstfloor.org> (raw)
In-Reply-To: <CANFySvcwE52VTqPKc5vzkQkq+wAenFr=deaGX8ZxGQFTU1SjVg@mail.gmail.com>
On Fri, May 01, 2015 at 09:31:58PM -0500, Chris Freehill wrote:
> A follow up...can you define what "sockets/nodes" means in this
> context? What is the relationship between sockets/nodes and CPU's.
In Linux terminology a CPU is a logical CPU thread. A socket
is a physical chip.
> What is the distinction? For core events, they would be the same,
> right? Could you give an example of what "-a" would sum up when we are
> talking about uncore events?
It sums up events from all sockets
>
> I think my main confusion is an assumption (up to now, anyway) that
> there is only one set of uncore events, for the multicore device, so
> it wouldn't make sense to sum up anything.
There is one set per socket (or rather chip, if you talk about an
multi-chip-module)
> For core events, my
> understanding is that with no "-C<core id>" specified, perf sums up
> the core event counts and presents this as output. For uncore, the
> events are not per-core, so I'm not sure how to interpret that "sum".
It's the sum of all cores on that socket.
-Andi
prev parent reply other threads:[~2015-05-02 12:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-01 20:55 perf uncore behavior Chris Freehill
2015-05-02 1:40 ` Andi Kleen
2015-05-02 2:31 ` Chris Freehill
2015-05-02 12:16 ` Andi Kleen [this message]
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