* Each CPU has a local buffer that stores PC value/event
* pairs. We also log context switches when we notice them.
* Eventually each CPU's buffer is processed into the global
- * event buffer by sync_cpu_buffers().
+ * event buffer by sync_buffer().
*
* We use a local buffer for two reasons: an NMI or similar
* interrupt cannot synchronise, and high sampling rates
#include <linux/errno.h>
#include "cpu_buffer.h"
+#include "buffer_sync.h"
#include "oprof.h"
struct oprofile_cpu_buffer cpu_buffer[NR_CPUS] __cacheline_aligned;
+static void wq_sync_buffer(void *);
+
+#define DEFAULT_TIMER_EXPIRE (HZ / 10)
+int work_enabled;
+
static void __free_cpu_buffers(int num)
{
int i;
- for (i=0; i < num; ++i) {
- struct oprofile_cpu_buffer * b = &cpu_buffer[i];
-
- if (!cpu_possible(i))
- continue;
-
- vfree(b->buffer);
+ for_each_online_cpu(i) {
+ if (cpu_buffer[i].buffer)
+ vfree(cpu_buffer[i].buffer);
}
}
unsigned long buffer_size = fs_cpu_buffer_size;
- for (i=0; i < NR_CPUS; ++i) {
+ for_each_online_cpu(i) {
struct oprofile_cpu_buffer * b = &cpu_buffer[i];
- if (!cpu_possible(i))
- continue;
-
b->buffer = vmalloc(sizeof(struct op_sample) * buffer_size);
if (!b->buffer)
goto fail;
b->head_pos = 0;
b->sample_received = 0;
b->sample_lost_overflow = 0;
- b->sample_lost_task_exit = 0;
+ b->cpu = i;
+ INIT_WORK(&b->work, wq_sync_buffer, b);
}
return 0;
+
fail:
__free_cpu_buffers(i);
return -ENOMEM;
}
+void start_cpu_work(void)
+{
+ int i;
+
+ work_enabled = 1;
+
+ for_each_online_cpu(i) {
+ struct oprofile_cpu_buffer * b = &cpu_buffer[i];
+
+ /*
+ * Spread the work by 1 jiffy per cpu so they dont all
+ * fire at once.
+ */
+ schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
+ }
+}
+
+
+void end_cpu_work(void)
+{
+ int i;
+
+ work_enabled = 0;
+
+ for_each_online_cpu(i) {
+ struct oprofile_cpu_buffer * b = &cpu_buffer[i];
+
+ cancel_delayed_work(&b->work);
+ }
+
+ flush_scheduled_work();
+}
+
+
/* compute number of available slots in cpu_buffer queue */
static unsigned long nr_available_slots(struct oprofile_cpu_buffer const * b)
{
/* notice a task switch */
if (cpu_buf->last_task != task) {
cpu_buf->last_task = task;
- if (!(task->flags & PF_EXITING)) {
- cpu_buf->buffer[cpu_buf->head_pos].eip = ~0UL;
- cpu_buf->buffer[cpu_buf->head_pos].event = (unsigned long)task;
- increment_head(cpu_buf);
- }
- }
-
- /* If the task is exiting it's not safe to take a sample
- * as the task_struct is about to be freed. We can't just
- * notify at release_task() time because of CLONE_DETACHED
- * tasks that release_task() themselves.
- */
- if (task->flags & PF_EXITING) {
- cpu_buf->sample_lost_task_exit++;
- return;
+ cpu_buf->buffer[cpu_buf->head_pos].eip = ~0UL;
+ cpu_buf->buffer[cpu_buf->head_pos].event = (unsigned long)task;
+ increment_head(cpu_buf);
}
cpu_buf->buffer[cpu_buf->head_pos].eip = eip;
cpu_buf->last_is_kernel = -1;
cpu_buf->last_task = NULL;
}
+
+
+/*
+ * This serves to avoid cpu buffer overflow, and makes sure
+ * the task mortuary progresses
+ *
+ * By using schedule_delayed_work_on and then schedule_delayed_work
+ * we guarantee this will stay on the correct cpu
+ */
+static void wq_sync_buffer(void * data)
+{
+ struct oprofile_cpu_buffer * b = (struct oprofile_cpu_buffer *)data;
+ if (b->cpu != smp_processor_id()) {
+ printk("WQ on CPU%d, prefer CPU%d\n",
+ smp_processor_id(), b->cpu);
+ }
+ sync_buffer(b->cpu);
+
+ /* don't re-add the work if we're shutting down */
+ if (work_enabled)
+ schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
+}