Re: [PATCH] perf tools: add support for lipfm4

On Wed, Mar 11, 2020 at 12:32:26PM -0700, Ian Rogers wrote:

On Wed, Mar 11, 2020 at 9:13 AM Jiri Olsa [off-list ref] wrote:

quoted

On Tue, Mar 10, 2020 at 02:39:23PM -0700, Stephane Eranian wrote:

quoted

On Tue, Mar 10, 2020 at 12:59 PM Andi Kleen [off-list ref] wrote:

quoted

On Tue, Mar 10, 2020 at 11:50:03AM -0700, Ian Rogers wrote:

quoted

This patch links perf with the libpfm4 library.
This library contains all the hardware event tables for all
processors supported by perf_events. This is a helper library
that help convert from a symbolic event name to the event
encoding required by the underlying kernel interface. This
library is open-source and available from: http://perfmon2.sf.net.

For most CPUs the builtin perf JSON event support should make
this redundant.

We decided to post this patch to propose an alternative to the JSON
file approach. It could be an option during the build.
The libpfm4 library has been around for 15 years now. Therefore, it
supports a lot of processors core and uncore and it  is very portable.
The key value add I see is that this is a library that can be, and has
been, used by tool developers directly in their apps. It can
work with more than Linux perf_events interface. It is not tied to the
interface. It has well defined and documented entry points.
We do use libpfm4 extensively at Google in both the perf tool and
applications. The PAPI toolkit also relies on this library.

I don't see this as competing with the JSON approach. It is just an
option I'd like to offer to users especially those familiar
with it in their apps.

I dont mind having it, in fact I found really old email where I'm
asking Peter about that ;-) and he wasn't very keen about that:
  https://lore.kernel.org/lkml/1312806326.10488.30.camel@twins/ (local)

not sure what was the actual reason at that time and if anything
changed since.. Peter?

btw I can't apply even that v2 on latest Arnaldo's branch

jirka

Thanks Jiri,

the patches were done on tip.git/master, perhaps there is a conflict
with the Documents Makefile due to adding better man page dates? I'll
try to repro building on
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/ on the
perf/core branch unless you  have a different suggestion? I also

yes, it's perf/core

jirka