linux-kernel - Re: [PATCH v7 0/4] Add support for parametrized events

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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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