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Commit 6accb9cf authored by Robert Richter's avatar Robert Richter Committed by Ingo Molnar
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perf/x86-ibs: Fix frequency profiling 



Fixing profiling at a fixed frequency, in this case the freq value and
sample period was setup incorrectly. Since sampling periods are
adjusted we also allow periods that have lower 4 bits set.

Another fix is the setup of the hw counter: If we modify
hwc->sample_period, we also need to update hwc->last_period and
hwc->period_left.

Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-5-git-send-email-robert.richter@amd.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7bf35238

arch/x86/kernel/cpu/perf_event_amd_ibs.c

+16 −2
Original line number Diff line number Diff line
@@ -162,9 +162,16 @@ static int perf_ibs_init(struct perf_event *event) 
		if (config & perf_ibs->cnt_mask)

			/* raw max_cnt may not be set */

			return -EINVAL;

		if (hwc->sample_period & 0x0f)

			/* lower 4 bits can not be set in ibs max cnt */

		if (!event->attr.sample_freq && hwc->sample_period & 0x0f)

			/*

			 * lower 4 bits can not be set in ibs max cnt,

			 * but allowing it in case we adjust the

			 * sample period to set a frequency.

			 */

			return -EINVAL;

		hwc->sample_period &= ~0x0FULL;

		if (!hwc->sample_period)

			hwc->sample_period = 0x10;

	} else {

		max_cnt = config & perf_ibs->cnt_mask;

		config &= ~perf_ibs->cnt_mask;
@@ -175,6 +182,13 @@ static int perf_ibs_init(struct perf_event *event) 
	if (!hwc->sample_period)

		return -EINVAL;



	/*

	 * If we modify hwc->sample_period, we also need to update

	 * hwc->last_period and hwc->period_left.

	 */

	hwc->last_period = hwc->sample_period;

	local64_set(&hwc->period_left, hwc->sample_period);



	hwc->config_base = perf_ibs->msr;

	hwc->config = config;