On Fri, 07 Nov, at 01:06:12PM, Peter Zijlstra wrote: > On Thu, Nov 06, 2014 at 12:23:21PM +0000, Matt Fleming wrote: > > +/* > > + * Exchange the RMID of a group of events. > > + */ > > +static unsigned int > > +intel_cqm_xchg_rmid(struct perf_event *group, unsigned int rmid) > > +{ > > + struct perf_event *event; > > + unsigned int old_rmid = group->hw.cqm_rmid; > > + struct list_head *head = &group->hw.cqm_group_entry; > > + > > + lockdep_assert_held(&cache_mutex); > > + > > + /* > > + * If our RMID is being deallocated, perform a read now. > > + */ > > + if (__rmid_valid(old_rmid) && !__rmid_valid(rmid)) { > > + struct intel_cqm_count_info info; > > + > > + local64_set(&group->count, 0); > > + info.event = group; > > + > > + preempt_disable(); > > + smp_call_function_many(&cqm_cpumask, __intel_cqm_event_count, > > + &info, 1); > > + preempt_enable(); > > + } > > This suffers the same issue as before, why not call that one function > and not reimplement it? > > Also, I don't think we'd ever swap an rmid for another valid one, right? > So we could do this read/update unconditionally.
No, we never swap a valid RMID for another valid one, but we do make a invalid -> valid transition, so doing the read wouldn't make sense in that situation. -- Matt Fleming, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/