Messages in this thread | | | Subject | Re: [PATCH v2 1/6] perf: Add interface to add general events to sysfs | From | Peter Zijlstra <> | Date | Mon, 25 Jul 2011 09:57:21 +0200 |
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On Tue, 2011-07-19 at 15:52 +0800, Lin Ming wrote:
> > I'd rather not have a function pointer here, and all the kobj thingies > > can be hooking into the existing struct device, right? > > I forgot to mention one important reason why I added a function pointer. > > The events can only be added to sysfs after PMU sysfs is initialized in > perf_event_sysfs_init -> > pmu_dev_alloc
Right.
> > @@ -5571,6 +5571,8 @@ static int pmu_dev_alloc(struct pmu *pmu) > > if (ret) > > goto free_dev; > > > > + if (pmu->add_events) > > + pmu->add_events(); > > So we need a pmu callback which is called in pmu_dev_alloc to add events > to sysfs. > > You suggested a new interface, > int perf_pmu_add_event(struct pmu *pmu, const char *name, u64 config) > > But where should it be called? > I guess you mean to call it in pmu init function, for example, > uncore_pmu_init. > > But pmu init function maybe called before perf_event_sysfs_init, which > means the pmu sysfs has not been initialized yet.
Right, so there is no reason to call perf_pmu_register() really early, except for the normal pmu and the software pmu (since they're used by the watchdog muck).
The uncore for example can use late_initcall() just fine and use both perf_pmu_register() and the proposed perf_pmu_add_event() from the same init call.
Only for the primary pmu and software thingies do we need to add an extra init call.
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