perf_error_detection.c

#include "perf_error_detection.h"
#include <linux/smp.h>

#define PERF_SAMPLE_PERIOD_SIZE		100000

/*
 * Our understanding of perf so far. Please correct as needed.
 *
 * An event in perf's terms is an instruction in our case.
 * A sample is a fixed number of events that CAN trigger a wakeup_event (but not the only way).
 * An overflow event is triggered by a fixed number of wakeup_event.
 *
 */

//initialize perf event for new task
int init_perf_event(struct plan_entry plan_entry, struct perf_event **pevent){
	struct perf_event_attr pe;

	//set perf_event_attr for init perf event
	memset(&pe, 0, sizeof(struct perf_event_attr));
	pe.type = PERF_TYPE_HARDWARE;
	pe.size = sizeof(struct perf_event_attr);
	pe.config = PERF_COUNT_HW_INSTRUCTIONS;
	pe.sample_period = plan_entry.n_instr;
	pe.disabled = 0;		// start the counter as soon as we're in userland
	pe.pinned = 1;			// ?
	pe.exclude_kernel = 1;
	pe.exclude_hv = 1;
	pe.precise_ip = 2;		// 2  SAMPLE_IP requested to have 0 skid.

	/* Not needed on 3.2? */
	pe.wakeup_events = 1;

	// cpu = -1 -> cpu indepented (assumed to be regulated by plan)
	*pevent = perf_event_create(&pe, smp_processor_id());

	if (IS_ERR(pevent)) {
			printk(KERN_WARNING "PB ERROR INITIALISING PERF EVENT\n");
			return -1;
	}

	return 0;
}


/*
 * Must not be called after the event is terminated.
 */
u64 get_perf_counter(struct perf_event *pevent, u64 *perf_counter)
{
	return perf_event_read_local(pevent, perf_counter);
}

u64 terminate_perf_event(struct perf_event *pevent)
{
	return perf_event_release_kernel(pevent);
}



//handle the perf overflow event -> task needed more instructions than planed
void overflow_handler(
		struct perf_event *event,
		struct perf_sample_data *data,
		struct pt_regs *regs)
{
	struct pb_rq *pb_rq;
	int cpu;

	cpu = smp_processor_id();
	pb_rq = &cpu_rq(cpu)->pb;


	printk(KERN_WARNING "PB TASK %llu RAN TOO LONG\n",pb_rq->plan[pb_rq->c_entry].task_id);

}

struct perf_event* perf_event_create(struct perf_event_attr *hw_event_uptr, int cpu)
{
	return perf_event_create_kernel_counter(
			hw_event_uptr,
			cpu,
			NULL, /* per CPU */
			&overflow_handler,
			NULL /* Was ist eigentlich context? */);
}