static int victim_child(union pipe read_pipe, union pipe write_pipe)
{
	FAIL_IF(wait_for_parent(read_pipe));

	/* Setup our EBB handler, before the EBB event is created */
	ebb_enable_pmc_counting(1);
	setup_ebb_handler(standard_ebb_callee);
	ebb_global_enable();

	FAIL_IF(notify_parent(write_pipe));

	while (ebb_state.stats.ebb_count < 20) {
		FAIL_IF(core_busy_loop());
	}

	ebb_global_disable();
	ebb_freeze_pmcs();

	count_pmc(1, sample_period);

	dump_ebb_state();

	FAIL_IF(ebb_state.stats.ebb_count == 0);

	return 0;
}
Example #2
0
static void ebb_callee(void)
{
	uint64_t siar, val;

	val = mfspr(SPRN_BESCR);
	if (!(val & BESCR_PMEO)) {
		ebb_state.stats.spurious++;
		goto out;
	}

	ebb_state.stats.ebb_count++;
	trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);

	/* Resets the PMC */
	count_pmc(1, sample_period);

out:
	if (ebb_state.stats.ebb_count == NUMBER_OF_EBBS)
		/* Reset but leave counters frozen */
		reset_ebb_with_clear_mask(MMCR0_PMAO);
	else
		/* Unfreezes */
		reset_ebb();

	/* Do some stuff to chew some cycles and pop the counter */
	siar = mfspr(SPRN_SIAR);
	trace_log_reg(ebb_state.trace, SPRN_SIAR, siar);

	val = mfspr(SPRN_PMC1);
	trace_log_reg(ebb_state.trace, SPRN_PMC1, val);

	val = mfspr(SPRN_MMCR0);
	trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
}
Example #3
0
int back_to_back_ebbs(void)
{
	struct event event;

	event_init_named(&event, 0x1001e, "cycles");
	event_leader_ebb_init(&event);

	event.attr.exclude_kernel = 1;
	event.attr.exclude_hv = 1;
	event.attr.exclude_idle = 1;

	FAIL_IF(event_open(&event));

	setup_ebb_handler(ebb_callee);

	FAIL_IF(ebb_event_enable(&event));

	sample_period = 5;

	ebb_freeze_pmcs();
	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
	ebb_global_enable();
	ebb_unfreeze_pmcs();

	while (ebb_state.stats.ebb_count < NUMBER_OF_EBBS)
		FAIL_IF(core_busy_loop());

	ebb_global_disable();
	ebb_freeze_pmcs();

	count_pmc(1, sample_period);

	dump_ebb_state();

	event_close(&event);

	FAIL_IF(ebb_state.stats.ebb_count != NUMBER_OF_EBBS);

	return 0;
}
static int test_body(void)
{
	int i, orig_period, max_period;
	struct event event;

	/* We use PMC4 to make sure the kernel switches all counters correctly */
	event_init_named(&event, 0x40002, "instructions");
	event_leader_ebb_init(&event);

	event.attr.exclude_kernel = 1;
	event.attr.exclude_hv = 1;
	event.attr.exclude_idle = 1;

	FAIL_IF(event_open(&event));

	ebb_enable_pmc_counting(4);
	setup_ebb_handler(standard_ebb_callee);
	ebb_global_enable();
	FAIL_IF(ebb_event_enable(&event));

	/*
	 * We want a low sample period, but we also want to get out of the EBB
	 * handler without tripping up again.
	 *
	 * This value picked after much experimentation.
	 */
	orig_period = max_period = sample_period = 400;

	mtspr(SPRN_PMC4, pmc_sample_period(sample_period));

	while (ebb_state.stats.ebb_count < 1000000) {
		/*
		 * We are trying to get the EBB exception to race exactly with
		 * us entering the kernel to do the syscall. We then need the
		 * kernel to decide our timeslice is up and context switch to
		 * the other thread. When we come back our EBB will have been
		 * lost and we'll spin in this while loop forever.
		 */

		for (i = 0; i < 100000; i++)
			sched_yield();

		/* Change the sample period slightly to try and hit the race */
		if (sample_period >= (orig_period + 200))
			sample_period = orig_period;
		else
			sample_period++;

		if (sample_period > max_period)
			max_period = sample_period;
	}

	ebb_freeze_pmcs();
	ebb_global_disable();

	count_pmc(4, sample_period);
	mtspr(SPRN_PMC4, 0xdead);

	dump_summary_ebb_state();
	dump_ebb_hw_state();

	event_close(&event);

	FAIL_IF(ebb_state.stats.ebb_count == 0);

	/* We vary our sample period so we need extra fudge here */
	FAIL_IF(!ebb_check_count(4, orig_period, 2 * (max_period - orig_period)));

	return 0;
}