msm: perf: tracectr: Initialize cnts after hotplug
Due to the mismatch between counter values saved across CPU hotplug
by perf and tracecounter logic, incorrect values are calculated for
first entry in trace buffer.
Ignore the first entry when CPU comes out of hotplug and set previous
counter values in this scenario.
Change-Id: Ieeeaa301d713f338f11f6e84aeb984a3708e45fc
Signed-off-by: Sheetal Sahasrabudhe <sheetals@codeaurora.org>
diff --git a/arch/arm/mach-msm/perf_trace_counters.c b/arch/arm/mach-msm/perf_trace_counters.c
index 0a679b1..8eb1244 100644
--- a/arch/arm/mach-msm/perf_trace_counters.c
+++ b/arch/arm/mach-msm/perf_trace_counters.c
@@ -21,21 +21,17 @@
DEFINE_PER_CPU(u32[NUM_L1_CTRS], previous_l1_cnts);
DEFINE_PER_CPU(u32[NUM_L2_PERCPU], previous_l2_cnts);
DEFINE_PER_CPU(u32, old_pid);
+DEFINE_PER_CPU(u32, hotplug_flag);
/* Reset per_cpu variables that store counter values uppn CPU hotplug */
static int tracectr_cpu_hotplug_notifier(struct notifier_block *self,
unsigned long action, void *hcpu)
{
int ret = NOTIFY_OK;
int cpu = (int)hcpu;
- int i;
- if ((action & (~CPU_TASKS_FROZEN)) == CPU_UP_PREPARE) {
- per_cpu(previous_ccnt, cpu) = 0;
- for (i = 0; i < NUM_L1_CTRS; i++)
- per_cpu(previous_l1_cnts[i], cpu) = 0;
- for (i = 0; i < NUM_L2_PERCPU; i++)
- per_cpu(previous_l2_cnts[i], cpu) = 0;
- }
+ if ((action & (~CPU_TASKS_FROZEN)) == CPU_STARTING)
+ per_cpu(hotplug_flag, cpu) = 1;
+
return ret;
}
@@ -43,6 +39,35 @@
.notifier_call = tracectr_cpu_hotplug_notifier,
};
+static void setup_prev_cnts(u32 cpu)
+{
+ int i;
+ u32 cnten_val;
+
+ /* Read PMCNTENSET */
+ asm volatile("mrc p15, 0, %0, c9, c12, 1" : "=r"(cnten_val));
+ /* Disable all the counters that were enabled */
+ asm volatile("mcr p15, 0, %0, c9, c12, 2" : : "r"(cnten_val));
+ if (cnten_val & CC) {
+ /* Read value */
+ asm volatile("mrc p15, 0, %0, c9, c13, 0"
+ : "=r"(per_cpu(previous_ccnt, cpu)));
+ }
+
+ for (i = 0; i < NUM_L1_CTRS; i++) {
+ if (cnten_val & (1 << i)) {
+ /* Select */
+ asm volatile("mcr p15, 0, %0, c9, c12, 5"
+ : : "r"(i));
+ /* Read value */
+ asm volatile("mrc p15, 0, %0, c9, c13, 2"
+ : "=r"(per_cpu(previous_l1_cnts[i], cpu)));
+ }
+ }
+ /* Enable all the counters that were disabled */
+ asm volatile("mcr p15, 0, %0, c9, c12, 1" : : "r"(cnten_val));
+}
+
static int tracectr_notifier(struct notifier_block *self, unsigned long cmd,
void *v)
{
@@ -54,9 +79,14 @@
return -EFAULT;
current_pid = thread->task->pid;
- if (per_cpu(old_pid, cpu) != -1)
- trace_sched_switch_with_ctrs(per_cpu(old_pid, cpu),
- current_pid);
+ if (per_cpu(old_pid, cpu) != -1) {
+ if (per_cpu(hotplug_flag, cpu) == 1) {
+ per_cpu(hotplug_flag, cpu) = 0;
+ setup_prev_cnts(cpu);
+ } else
+ trace_sched_switch_with_ctrs(per_cpu(old_pid, cpu),
+ current_pid);
+ }
per_cpu(old_pid, cpu) = current_pid;
return NOTIFY_OK;
}