Hi Stephane,
I am still looking at this code with the idea of trying to eliminate the
libpfm4 changes while at the same time not duplicating libpfm4 code in PAPI.
I found the libpfm4 function pfm_get_event_next which I now use to step through
the events on a pmu when PAPI lists events. This has eliminated the need for
PAPI to use the function pfmlib_idx2pidx.
The other libpfm4 funtion which papi is still using is idx2pmu. This function
is used by PAPI after listing the last event on a pmu. It gives PAPI the pmu
number from the last event processed. This is needed so we can find the next
pmu of a particular type then we get the first event from the next pmu to
continue listing events.
Does libpfm4 provide another way for PAPI to get the next pmu of a particular
type ??
Maybe a libpfm4 function like pfm_get_pmu_next (int idx) would be the best way
to solve this problem.
If you like this approach, I can build one and get it working with PAPI.
If you have a different suggestion, please share it.
Thanks
Gary
From: Gary Mohr
Sent: Monday, May 05, 2014 3:41 PM
To: 'Stephane Eranian'
Cc: 'Philip Mucci'; Vince Weaver; 'Heike McCraw';
'<perfapi-de...@eecs.utk.edu>'; 'perfmon2-devel'
Subject: RE: [Perfapi-devel] [perfmon2] FW: Proposed enhancement to libpfm4.
Hi Stephane,
Following your suggestions, I have modified PAPI to no longer use
pfm_find_event(). This has eliminated the problems I was seeing when trying to
use PFM_OS_PERF_EVENT_EXT through the PAPI API. I have also restructured PAPI
to separate the code paths used when listing events and when counting events.
This has simplified both of these code paths quite a bit. Currently I only
have this new code working in the perf_events component but I plan to also put
the same modifications into the perf_events_uncore component.
While doing this work I found that PAPI needed two functions which exist in
libpfm4 but were declared as static so they were not available to PAPI. The
functions are idx2pmu and pfmlib_idx2pidx.
The attached patch file modifies libpfm4 to make these two functions externally
visible so that PAPI can use them.
Would be willing to commit this change to libpfm4 or should I replicate the
source for these two functions in PAPI ?
If you would prefer to provide functions by different names which do the same
thing, that would be fine with me (the existing names are not really the kind
of name I would expect to find in a libraries API).
Let me know how you would like to handle this.
Thanks
Gary
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