On Fri, 9 Mar 2018, Peter Zijlstra wrote: > On Fri, Mar 09, 2018 at 09:31:11AM -0500, Vince Weaver wrote: > > On Fri, 9 Mar 2018, tip-bot for Kan Liang wrote: > > > > > Commit-ID: 1af22eba248efe2de25658041a80a3d40fb3e92e > > > Gitweb: > > > https://git.kernel.org/tip/1af22eba248efe2de25658041a80a3d40fb3e92e > > > Author: Kan Liang <kan.li...@linux.intel.com> > > > AuthorDate: Mon, 12 Feb 2018 14:20:35 -0800 > > > Committer: Ingo Molnar <mi...@kernel.org> > > > CommitDate: Fri, 9 Mar 2018 08:22:23 +0100 > > > > > > perf/x86/intel: Disable userspace RDPMC usage for large PEBS > > > > > > > > > So this whole commit log is about disabling RDPMC usage for "large PEBS" > > but the actual change disables RDPMC if "PERF_X86_EVENT_FREERUNNING" > > > > Either the commit log is really misleading, or else a poor name was chosen > > for this feature. > > Its the same thing, and yes that might want renaming I suppose.
I apologize for noticing these things so late in the game, but I haven't had time to keep up with a full lkml feed recently so I only see these things once I'm CC'd on them. So to summarize this: rdpmc is only disabled on a per-event basis, and only if that event is doing multi-pebs sampling? If that's true, then I don't think I have an issue with this. We finally got rdpmc support in a released PAPI, and it is a massive improvement when self-monitoring (even moreso if KPTI is enabled) so I was just trying to make sure this wouldn't suddenly disable rdpmc out from under us. Vince
