2017-03-10 06:29:14

by Anurup M

Subject: [PATCH v6 10/11] drivers: perf: hisi: use poll method when no IRQ for MN counter overflow

When no IRQ is supported in hardware, use hrtimer to poll and
update event counter and avoid overflow condition for MN PMU.
An interval of 8 seconds is used for the hrtimer.

Signed-off-by: Anurup M <[email protected]>
Signed-off-by: Shaokun Zhang <[email protected]>
Signed-off-by: Dikshit N <[email protected]>
---
drivers/perf/hisilicon/hisi_uncore_mn.c | 39 +++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)

diff --git a/drivers/perf/hisilicon/hisi_uncore_mn.c b/drivers/perf/hisilicon/hisi_uncore_mn.c
index 18316dc..55b6165 100644
--- a/drivers/perf/hisilicon/hisi_uncore_mn.c
+++ b/drivers/perf/hisilicon/hisi_uncore_mn.c
@@ -20,6 +20,8 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/bitmap.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
@@ -56,6 +58,15 @@ enum armv8_hisi_mn_counters {

#define GET_MODULE_ID(hwmod_data) hwmod_data->mn_hwcfg.module_id

+/*
+ * Default timer frequency to poll and avoid counter overflow.
+ * CPU speed = 2.4Ghz and number of CPU cores in a SCCL is 16.
+ * For a single MN event on a CPU core consumes 200 cycles.
+ * So overflow time = (2^31 * 200) / (16 * 2.4G) which is about 21 seconds
+ * So on a safe side we use a timer interval of 8sec
+ */
+#define MN1_HRTIMER_INTERVAL (8LL * MSEC_PER_SEC)
+
struct hisi_mn_hwcfg {
u32 module_id;
};
@@ -272,6 +283,15 @@ static const struct of_device_id mn_of_match[] = {
};
MODULE_DEVICE_TABLE(of, mn_of_match);

+/* Use hrtimer when no IRQ, to poll for avoiding counter overflow */
+static void hisi_mn_hrtimer_init(struct hisi_pmu *mn_pmu)
+{
+ INIT_LIST_HEAD(&mn_pmu->active_list);
+ mn_pmu->ops->start_hrtimer = hisi_hrtimer_start;
+ mn_pmu->ops->stop_hrtimer = hisi_hrtimer_stop;
+ hisi_hrtimer_init(mn_pmu, MN1_HRTIMER_INTERVAL);
+}
+
static int hisi_mn_init_data(struct hisi_pmu *mn_pmu,
struct hisi_djtag_client *client)
{
@@ -314,6 +334,12 @@ static int hisi_mn_init_data(struct hisi_pmu *mn_pmu,
} else
return -EINVAL;

+ /*
+ * Use poll method to avoid counter overflow as
+ * overflow IRQ is not supported in hardware.
+ */
+ hisi_mn_hrtimer_init(mn_pmu);
+
return 0;
}

@@ -361,11 +387,24 @@ static const struct attribute_group hisi_mn_cpumask_attr_group = {
.attrs = hisi_mn_cpumask_attrs,
};

+static DEVICE_ATTR(hrtimer_interval, 0444, hisi_hrtimer_interval_sysfs_show,
+ NULL);
+
+static struct attribute *hisi_mn_hrtimer_interval_attrs[] = {
+ &dev_attr_hrtimer_interval.attr,
+ NULL,
+};
+
+static const struct attribute_group hisi_mn_hrtimer_interval_attr_group = {
+ .attrs = hisi_mn_hrtimer_interval_attrs,
+};
+
static const struct attribute_group *hisi_mn_pmu_attr_groups[] = {
&hisi_mn_attr_group,
&hisi_mn_format_group,
&hisi_mn_events_group,
&hisi_mn_cpumask_attr_group,
+ &hisi_mn_hrtimer_interval_attr_group,
NULL,
};

--
2.1.4

2017-03-21 17:19:17

by Mark Rutland

Subject: Re: [PATCH v6 10/11] drivers: perf: hisi: use poll method when no IRQ for MN counter overflow

On Fri, Mar 10, 2017 at 01:29:01AM -0500, Anurup M wrote:
> When no IRQ is supported in hardware, use hrtimer to poll and
> update event counter and avoid overflow condition for MN PMU.
> An interval of 8 seconds is used for the hrtimer.

Please fold this into the main MN patch.

The comments on the L3 hrtimer patch also apply here.

Thanks,
Mark.

2017-03-24 06:43:56

by Anurup M

Subject: Re: [PATCH v6 10/11] drivers: perf: hisi: use poll method when no IRQ for MN counter overflow

On Tuesday 21 March 2017 10:47 PM, Mark Rutland wrote:
> On Fri, Mar 10, 2017 at 01:29:01AM -0500, Anurup M wrote:
>> When no IRQ is supported in hardware, use hrtimer to poll and
>> update event counter and avoid overflow condition for MN PMU.
>> An interval of 8 seconds is used for the hrtimer.
> Please fold this into the main MN patch.
>
> The comments on the L3 hrtimer patch also apply here.

Sure. shall fix these comments. and fold to main MN patch.

Thanks,
Anurup

> Thanks,
> Mark.