perf, x86: Fix AMD hotplug & constraint initialization
Commit 3f6da39 ("perf: Rework and fix the arch CPU-hotplug hooks") moved
the amd northbridge allocation from CPUS_ONLINE to CPUS_PREPARE_UP
however amd_nb_id() doesn't work yet on prepare so it would simply bail
basically reverting to a state where we do not properly track node wide
constraints - causing weird perf results.
Fix up the AMD NorthBridge initialization code by allocating from
CPU_UP_PREPARE and installing it from CPU_STARTING once we have the
proper nb_id. It also properly deals with the allocation failing.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
[ robustify using amd_has_nb() ]
Signed-off-by: Stephane Eranian <eranian@google.com>
LKML-Reference: <1269353485.5109.48.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
index b87e0b6..db6f7d4 100644
--- a/arch/x86/kernel/cpu/perf_event_amd.c
+++ b/arch/x86/kernel/cpu/perf_event_amd.c
@@ -137,6 +137,13 @@
return (hwc->config & 0xe0) == 0xe0;
}
+static inline int amd_has_nb(struct cpu_hw_events *cpuc)
+{
+ struct amd_nb *nb = cpuc->amd_nb;
+
+ return nb && nb->nb_id != -1;
+}
+
static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
struct perf_event *event)
{
@@ -147,7 +154,7 @@
/*
* only care about NB events
*/
- if (!(nb && amd_is_nb_event(hwc)))
+ if (!(amd_has_nb(cpuc) && amd_is_nb_event(hwc)))
return;
/*
@@ -214,7 +221,7 @@
/*
* if not NB event or no NB, then no constraints
*/
- if (!(nb && amd_is_nb_event(hwc)))
+ if (!(amd_has_nb(cpuc) && amd_is_nb_event(hwc)))
return &unconstrained;
/*
@@ -293,51 +300,55 @@
return nb;
}
-static void amd_pmu_cpu_online(int cpu)
+static int amd_pmu_cpu_prepare(int cpu)
{
- struct cpu_hw_events *cpu1, *cpu2;
- struct amd_nb *nb = NULL;
+ struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
+
+ WARN_ON_ONCE(cpuc->amd_nb);
+
+ if (boot_cpu_data.x86_max_cores < 2)
+ return NOTIFY_OK;
+
+ cpuc->amd_nb = amd_alloc_nb(cpu, -1);
+ if (!cpuc->amd_nb)
+ return NOTIFY_BAD;
+
+ return NOTIFY_OK;
+}
+
+static void amd_pmu_cpu_starting(int cpu)
+{
+ struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
+ struct amd_nb *nb;
int i, nb_id;
if (boot_cpu_data.x86_max_cores < 2)
return;
- /*
- * function may be called too early in the
- * boot process, in which case nb_id is bogus
- */
nb_id = amd_get_nb_id(cpu);
- if (nb_id == BAD_APICID)
- return;
-
- cpu1 = &per_cpu(cpu_hw_events, cpu);
- cpu1->amd_nb = NULL;
+ WARN_ON_ONCE(nb_id == BAD_APICID);
raw_spin_lock(&amd_nb_lock);
for_each_online_cpu(i) {
- cpu2 = &per_cpu(cpu_hw_events, i);
- nb = cpu2->amd_nb;
- if (!nb)
+ nb = per_cpu(cpu_hw_events, i).amd_nb;
+ if (WARN_ON_ONCE(!nb))
continue;
- if (nb->nb_id == nb_id)
- goto found;
+
+ if (nb->nb_id == nb_id) {
+ kfree(cpuc->amd_nb);
+ cpuc->amd_nb = nb;
+ break;
+ }
}
- nb = amd_alloc_nb(cpu, nb_id);
- if (!nb) {
- pr_err("perf_events: failed NB allocation for CPU%d\n", cpu);
- raw_spin_unlock(&amd_nb_lock);
- return;
- }
-found:
- nb->refcnt++;
- cpu1->amd_nb = nb;
+ cpuc->amd_nb->nb_id = nb_id;
+ cpuc->amd_nb->refcnt++;
raw_spin_unlock(&amd_nb_lock);
}
-static void amd_pmu_cpu_offline(int cpu)
+static void amd_pmu_cpu_dead(int cpu)
{
struct cpu_hw_events *cpuhw;
@@ -349,8 +360,10 @@
raw_spin_lock(&amd_nb_lock);
if (cpuhw->amd_nb) {
- if (--cpuhw->amd_nb->refcnt == 0)
- kfree(cpuhw->amd_nb);
+ struct amd_nb *nb = cpuhw->amd_nb;
+
+ if (nb->nb_id == -1 || --nb->refcnt == 0)
+ kfree(nb);
cpuhw->amd_nb = NULL;
}
@@ -379,8 +392,9 @@
.get_event_constraints = amd_get_event_constraints,
.put_event_constraints = amd_put_event_constraints,
- .cpu_prepare = amd_pmu_cpu_online,
- .cpu_dead = amd_pmu_cpu_offline,
+ .cpu_prepare = amd_pmu_cpu_prepare,
+ .cpu_starting = amd_pmu_cpu_starting,
+ .cpu_dead = amd_pmu_cpu_dead,
};
static __init int amd_pmu_init(void)
