Hi Stephane, I recently modified the perf tool to use libpfm4 (the modifications are against 2.6.31, and I haven't posted them to LKML yet).
One issue I ran into, though, is error checking in libpfm4 is not real helpful to a user. Basically, if they supply an incorrect event specification string, libpfm4 just returns PFM_ERR_INVAL, and doesn't give them much of a clue as to what exactly is wrong. My first thought was that the error code is ok, but inside the arch specific code, I need to do a better job of emitting error messsages via DPRINT, as is done for x86 processors in pfmlib_intel_x86.c for example. So I added a bunch of DPRINT statements, and then enabled debug output via the environment variable "LIBPFM_DEBUG", set to "1". Using this technique, I do indeed get error message output, but I also get a *lot* of other narrative output, mostly from get_tracepoint_table in pfmlib_perf_event_pmu.c. So I have temporarily disabled the output from that function in my local copy of libpfm4. I see another mechanism in libpfm4, LIBPFM_VERBOSE. If it is set, calls to __pfm_vbprintf funnel output to stderr or stdout (if LIBPFM_DEBUG_STDOUT is set). There are a lot of usages of __pfm_vbprintf in the arch-specific code, but it all appears to be narrative/debug information, instead of verbose error messages. What is the intention behind these two environment variables. Do you have suggestions as to which way to go with this? Should there be a level or mask code introduced into the DPRINT statement, so users can be a bit more selective about what output they want? Should the usage for these two mechanisms be spelled out? Should the code in get_tracepoint_table be changed to use __pfm_vbprintf instead of DPRINT? There's no rush on this, but I think it's an area that could use some refinement. Thanks for your consideration, - Corey Corey Ashford Software Engineer IBM Linux Technology Center, Linux Toolchain Beaverton, OR 503-578-3507 cjash...@us.ibm.com ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
