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Message-ID: <20150108095434.GA16059@krava.redhat.com>
Date: Thu, 8 Jan 2015 10:54:34 +0100
From: Jiri Olsa <jolsa@...hat.com>
To: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>,
Paul Mackerras <paulus@...ba.org>, dev@...yps.com,
peterz@...radead.org, hbabu@...ibm.com,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v7 0/4] Add support for parametrized events
On Wed, Jan 07, 2015 at 05:13:49PM -0800, Sukadev Bhattiprolu wrote:
> Description of "event parameters" from the documentation patch:
>
> Event parameters are a basic way for partial events to be specified in
> sysfs with per-event names given to the fields that need to be filled in
> when using a particular event.
>
> It is intended for supporting cases where the single 'cpu' parameter is
> insufficient. For example, POWER 8 has events for physical
> sockets/cores/cpus that are accessible from with virtual machines. To
> keep using the single 'cpu' parameter we'd need to perform a mapping
> between Linux's cpus and the physical machine's cpus (in this case
> Linux is running under a hypervisor). This isn't possible because
> bindings between our cpus and physical cpus may not be fixed, and we
> probably won't have a "cpu" on each physical cpu.
>
> Description of the sysfs contents when events are parameterized (copied from an
> included patch):
>
> Examples:
>
> domain=0x1,offset=0x8,core=?
>
> In the case of the last example, a value replacing "?" would need
> to be provided by the user selecting the particular event. This is
> refered to as "event parameterization". All non-numerical values
> indicate an event parameter.
>
> Notes on how perf-list displays parameterized events
>
> PARAMETERIZED EVENTS
> --------------------
>
> Some pmu events listed by 'perf list' will be displayed with '$xyz' in
> them. For example:
>
> hv_24x7/HPM_THREAD_NAP_CCYC__PHYS_CORE,core=?/
>
> This means that when provided as an event, a value for ? must also
> be supplied. For example:
>
> perf stat -e \
> 'hv_24x7/HPM_THREAD_NAP_CCYC__PHYS_CORE,core=2' ...
>
> Changelog[v7]
> [Jiri Olsa] Nit: Add braces for clarity.
> [Jiri Olsa] Add a check to make sure that sysfs entries have with
> parameters exactly match '=?'.
for the patchset:
Acked-by: Jiri Olsa <jolsa@...nel.org>
thanks,
jirka
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