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SubjectRe: [PATCH v7] perf tools: add support for libpfm4
On Tue, Apr 7, 2020 at 1:25 PM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Mon, Apr 06, 2020 at 11:40:18PM -0700, Ian Rogers wrote:
> > From: Stephane Eranian <eranian@google.com>
> >
> > This patch links perf with the libpfm4 library if it is available and
> > NO_LIBPFM4 isn't passed to the build. The libpfm4 library contains hardware
> > event tables for all processors supported by perf_events. It is a helper
> > library that helps 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.
> >
> > With this patch, it is possible to specify full hardware events
> > by name. Hardware filters are also supported. Events must be
> > specified via the --pfm-events and not -e option. Both options
> > are active at the same time and it is possible to mix and match:
> >
> > $ perf stat --pfm-events inst_retired:any_p:c=1:i -e cycles ....
> >
> > v7 rebases and adds fallback code for libpfm4 events.
> > The fallback code is to force user only priv level in case the
> > perf_event_open() syscall failed for permissions reason.
> > the fallback forces a user privilege level restriction on the event string,
> > so depending on the syntax either u or :u is needed.
> >
> > But libpfm4 can use a : or . as the separator, so simply searching
> > for ':' vs. '/' is not good enough to determine the syntax needed.
> > Therefore, this patch introduces a new evsel boolean field to mark events
> > coming from libpfm4. The field is then used to adjust the fallback string.
>
> heya,
> I made bunch of comments for v5, not sure you saw them:
> https://lore.kernel.org/lkml/20200323235846.104937-1-irogers@google.com/
>
> jirka

Sorry for missing this, I will work on fixing these and thanks!

Ian

> > v6 is a rebase.
> > v5 is a rebase.
> > v4 is a rebase on git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git
> > branch perf/core and re-adds the tools/build/feature/test-libpfm4.c
> > missed in v3.
> > v3 is against acme/perf/core and removes a diagnostic warning.
> > v2 of this patch makes the --pfm-events man page documentation
> > conditional on libpfm4 behing configured. It tidies some of the
> > documentation and adds the feature test missed in the v1 patch.
> >
>
> SNIP
>

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