Re: [RFC] [PATCH 1/1] perf: add support for arch-dependent symbolicevent names to "perf stat"

From: Corey Ashford
Date: Thu Mar 11 2010 - 15:46:27 EST




On 3/11/2010 11:14 AM, Ingo Molnar wrote:

* Corey Ashford<cjashfor@xxxxxxxxxxxxxxxxxx> wrote:
[snip]
I'm not sure how that would work. The issue I am trying to solve
here is that Power arch chips have a large number of very
hardware-specific events that are not generalizable. Many of these
events not only have names, but other user-configurable bits as well
that select or narrow the scope of which exact events are recorded.
This issue is dealt with nicely in libpfm4, as it has mechanisms for
parsing event names and attributes (aka modifiers or unit masks),
and then produces a usable config field for the perf_events_attr
struct.

Should I take it from the above that you are completely against the
idea of using an external library for hardware-specific event and
attribute naming?

Could you give a few relevant examples of events in question, and the kind of
configurability/attributes they have on Power?

Here are a few examples for the Power A2 processor. I've distorted the names because PMU architecture isn't publicly released yet.

PM_DE_PMC_9:hrd_mask=0xff:hrd=0x22:pma_mask=0x3fff:pma=0x1b2d:culling_mode=3
PM_EX_0x03:lane=2:vlane=1
PM_OWE_ENG_MAC_FULL:usu=3

Note that the attribute fields shown above are fitted into the config field of the perf_event_attr struct.


Thanks,

Ingo

Regards,

- Corey

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