perf/x86/intel/cqm: Get rid of the silly for_each_cpu() lookups

CQM is a strict per package facility. Use the proper cpumasks to lookup the
readers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Harish Chegondi <harish.chegondi@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20160222221012.054916179@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 1b064c4..93cb412 100644 (file)
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -1244,15 +1244,12 @@ static struct pmu intel_cqm_pmu = {
 
 static inline void cqm_pick_event_reader(int cpu)
 {
-       int phys_id = topology_physical_package_id(cpu);
-       int i;
+       int reader;
 
-       for_each_cpu(i, &cqm_cpumask) {
-               if (phys_id == topology_physical_package_id(i))
-                       return; /* already got reader for this socket */
-       }
-
-       cpumask_set_cpu(cpu, &cqm_cpumask);
+       /* First online cpu in package becomes the reader */
+       reader = cpumask_any_and(&cqm_cpumask, topology_core_cpumask(cpu));
+       if (reader >= nr_cpu_ids)
+               cpumask_set_cpu(cpu, &cqm_cpumask);
 }
 
 static void intel_cqm_cpu_starting(unsigned int cpu)
@@ -1270,24 +1267,17 @@ static void intel_cqm_cpu_starting(unsigned int cpu)
 
 static void intel_cqm_cpu_exit(unsigned int cpu)
 {
-       int phys_id = topology_physical_package_id(cpu);
-       int i;
+       int target;
 
-       /*
-        * Is @cpu a designated cqm reader?
-        */
+       /* Is @cpu the current cqm reader for this package ? */
        if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask))
                return;
 
-       for_each_online_cpu(i) {
-               if (i == cpu)
-                       continue;
+       /* Find another online reader in this package */
+       target = cpumask_any_but(topology_core_cpumask(cpu), cpu);
 
-               if (phys_id == topology_physical_package_id(i)) {
-                       cpumask_set_cpu(i, &cqm_cpumask);
-                       break;
-               }
-       }
+       if (target < nr_cpu_ids)
+               cpumask_set_cpu(target, &cqm_cpumask);
 }
 
 static int intel_cqm_cpu_notifier(struct notifier_block *nb,