Messages in this thread | | | Date | Tue, 4 Oct 2011 10:54:09 +0200 | From | Ingo Molnar <> | Subject | Re: [V3][PATCH 0/7] perf, x86: Implement AMD IBS |
| |
* Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, 2011-09-23 at 14:20 +0200, Robert Richter wrote: > > > The only thing I'm not quite sure on is the userspace bits, but those > > > are in the future work section as well, but possibly Ingo has a strong > > > opinion here, sadly he doesn't have email atm :/ > > > > With Lin's patch 'perf: Remove perf_event_attr::type check' we already > > can sample with perf record. > > > > I think we could extend perf report to parse also ibs samples. > > The only thing we need for it should be the pmu name/type mapping > > in the perf.data header and the pmu type in the sample. See my > > comment on Stephane's patch '[PATCH] perf: make perf.data more > > self-descriptive (v5)'. > > OK, so Ingo really really wants to see a little more perf > integration there. Acme, what's the state of Stephane's patch?
So the whole IBS thing looks quite unintegrated to me - and that's partly because the hw is admittedly weird. The way we could perhaps live with it upstream is two conditions:
- Testable IBS user-space code a bit more prominently integrated than having to go down into a cellar with no working lights and finding the code on display in tools/perf/Documentation/examples/ on the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying 'Beware of the Leopard.'
- Only root/privileged users should be able to access it. Right now i think it's root-only due to percpu restrictions, but wanted to mention it that this is an explicit requirement.
Non-privileged IBS use could be enabled by having working integration with generic events: we could add a upos generic event for example so IBS could map to '-e uops:p' or such, to allow skid-less profiling on AMD CPUs.
Thanks,
Ingo
| |