perf/x86/intel/rapl: Calculate timing once

No point in doing the same calculation over and over. Do it once in
rapl_check_hw_unit().

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/20160222221012.409238136@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/rapl.c b/arch/x86/events/intel/rapl.c
index 976558a..b1d4a2f 100644 (file)
--- a/arch/x86/events/intel/rapl.c
+++ b/arch/x86/events/intel/rapl.c
@@ -129,6 +129,7 @@ static int rapl_hw_unit[NR_RAPL_DOMAINS] __read_mostly;  /* 1/2^hw_unit Joule */
 static struct pmu rapl_pmu_class;
 static cpumask_t rapl_cpu_mask;
 static int rapl_cntr_mask;
+static u64 rapl_timer_ms;
 
 static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu);
 static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu_to_free);
@@ -558,7 +559,6 @@ static int rapl_cpu_prepare(int cpu)
 {
        struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
        int phys_id = topology_physical_package_id(cpu);
-       u64 ms;
 
        if (pmu)
                return 0;
@@ -575,19 +575,7 @@ static int rapl_cpu_prepare(int cpu)
 
        pmu->pmu = &rapl_pmu_class;
 
-       /*
-        * use reference of 200W for scaling the timeout
-        * to avoid missing counter overflows.
-        * 200W = 200 Joules/sec
-        * divide interval by 2 to avoid lockstep (2 * 100)
-        * if hw unit is 32, then we use 2 ms 1/200/2
-        */
-       if (rapl_hw_unit[0] < 32)
-               ms = (1000 / (2 * 100)) * (1ULL << (32 - rapl_hw_unit[0] - 1));
-       else
-               ms = 2;
-
-       pmu->timer_interval = ms_to_ktime(ms);
+       pmu->timer_interval = ms_to_ktime(rapl_timer_ms);
 
        rapl_hrtimer_init(pmu);
 
@@ -676,6 +664,19 @@ static int rapl_check_hw_unit(void (*quirk)(void))
        /* Apply cpu model quirk */
        if (quirk)
                quirk();
+
+       /*
+        * Calculate the timer rate:
+        * Use reference of 200W for scaling the timeout to avoid counter
+        * overflows. 200W = 200 Joules/sec
+        * Divide interval by 2 to avoid lockstep (2 * 100)
+        * if hw unit is 32, then we use 2 ms 1/200/2
+        */
+       rapl_timer_ms = 2;
+       if (rapl_hw_unit[0] < 32) {
+               rapl_timer_ms = (1000 / (2 * 100));
+               rapl_timer_ms *= (1ULL << (32 - rapl_hw_unit[0] - 1));
+       }
        return 0;
 }
 
@@ -695,9 +696,7 @@ static const struct x86_cpu_id rapl_cpu_match[] = {
 static int __init rapl_pmu_init(void)
 {
        void (*quirk)(void) = NULL;
-       struct rapl_pmu *pmu;
-       int cpu, ret;
-       int i;
+       int cpu, ret, i;
 
        /*
         * check for Intel processor family 6
@@ -758,15 +757,14 @@ static int __init rapl_pmu_init(void)
        }
 
        __perf_cpu_notifier(rapl_cpu_notifier);
-
-       pmu = __this_cpu_read(rapl_pmu);
+       cpu_notifier_register_done();
 
        pr_info("RAPL PMU detected,"
                " API unit is 2^-32 Joules,"
                " %d fixed counters"
                " %llu ms ovfl timer\n",
                hweight32(rapl_cntr_mask),
-               ktime_to_ms(pmu->timer_interval));
+               rapl_timer_ms);
        for (i = 0; i < NR_RAPL_DOMAINS; i++) {
                if (rapl_cntr_mask & (1 << i)) {
                        pr_info("hw unit of domain %s 2^-%d Joules\n",
@@ -774,7 +772,6 @@ static int __init rapl_pmu_init(void)
                }
        }
 
-       cpu_notifier_register_done();
        return 0;
 
 out: