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Commit 4088fdc4 authored by Santosh Mardi's avatar Santosh Mardi Committed by Gerrit - the friendly Code Review server
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PM / devfreq: memlat: Add writeback percentage as a lat condition 



Certain L3 workloads are latency sensitive to cache snoop traffic and
this traffic is not directly quantified in the existing memlat scheme.

Use L2 writeback percentage as a metric to identify snoop traffic to
improve memlat.

Change-Id: I9d43375d96de5a199c6a87c55e5c1079549b23ce
Signed-off-by: default avatarSantosh Mardi <gsantosh@codeaurora.org>
parent 725421da

drivers/devfreq/arm-memlat-mon.c

+76 −0
Original line number Diff line number Diff line
@@ -65,8 +65,20 @@ struct cpu_data { 
 *				defaults to using all of @cpu_grp's CPUs.

 * @miss_ev_id:			The event code corresponding to the @miss_ev

 *				perf event. Will be 0 for compute.

 * @access_ev_id:		The event code corresponding to the @access_ev

 *				perf event. Optional - only needed for writeback

 *				percent.

 * @wb_ev_id:			The event code corresponding to the @wb_ev perf

 *				event. Optional - only needed for writeback

 *				percent.

 * @miss_ev:			The cache miss perf event exclusive to this

 *				mon. Will be NULL for compute.

 * @access_ev:			The cache access perf event exclusive to this

 *				mon. Optional - only needed for writeback

 *				percent.

 * @wb_ev:			The cache writeback perf event exclusive to this

 *				mon. Optional - only needed for writeback

 *				percent.

 * @requested_update_ms:	The mon's desired polling rate. The lowest

 *				@requested_update_ms of all mons determines

 *				@cpu_grp's update_ms.
@@ -78,8 +90,12 @@ struct memlat_mon { 
	bool			is_active;

	cpumask_t		cpus;

	unsigned int		miss_ev_id;

	unsigned int		access_ev_id;

	unsigned int		wb_ev_id;

	unsigned int		requested_update_ms;

	struct event_data	*miss_ev;

	struct event_data	*access_ev;

	struct event_data	*wb_ev;

	struct memlat_hwmon	hw;



	struct memlat_cpu_grp	*cpu_grp;
@@ -191,6 +207,11 @@ static void update_counts(struct memlat_cpu_grp *cpu_grp) 
			unsigned int mon_idx =

				cpu - cpumask_first(&mon->cpus);

			read_event(&mon->miss_ev[mon_idx]);



			if (mon->wb_ev_id && mon->access_ev_id) {

				read_event(&mon->wb_ev[mon_idx]);

				read_event(&mon->access_ev[mon_idx]);

			}

		}

	}

}
@@ -219,6 +240,13 @@ static unsigned long get_cnt(struct memlat_hwmon *hw) 
			devstats->inst_count = 0;

			devstats->mem_count = 1;

		}



		if (mon->access_ev_id && mon->wb_ev_id)

			devstats->wb_pct =

				mult_frac(100, mon->wb_ev[mon_idx].last_delta,

					  mon->access_ev[mon_idx].last_delta);

		else

			devstats->wb_pct = 0;

	}



	return 0;
@@ -365,6 +393,18 @@ static int start_hwmon(struct memlat_hwmon *hw) 
					mon->miss_ev_id, attr);

			if (ret)

				goto unlock_out;



			if (mon->access_ev_id && mon->wb_ev_id) {

				ret = set_event(&mon->access_ev[idx], cpu,

						mon->access_ev_id, attr);

				if (ret)

					goto unlock_out;



				ret = set_event(&mon->wb_ev[idx], cpu,

						mon->wb_ev_id, attr);

				if (ret)

					goto unlock_out;

			}

		}

	}
@@ -401,6 +441,7 @@ static void stop_hwmon(struct memlat_hwmon *hw) 
		devstats->mem_count = 0;

		devstats->freq = 0;

		devstats->stall_pct = 0;

		devstats->wb_pct = 0;

	}



	if (!cpu_grp->num_active_mons) {
@@ -648,6 +689,8 @@ static int memlat_mon_probe(struct platform_device *pdev, bool is_compute) 
	 */

	if (is_compute) {

		mon->miss_ev_id = 0;

		mon->access_ev_id = 0;

		mon->wb_ev_id = 0;

		ret = register_compute(dev, hw);

	} else {

		mon->miss_ev =
@@ -668,6 +711,39 @@ static int memlat_mon_probe(struct platform_device *pdev, bool is_compute) 
		}

		mon->miss_ev_id = event_id;



		ret = of_property_read_u32(dev->of_node, "qcom,access-ev",

					   &event_id);

		if (ret)

			dev_dbg(dev, "Access event not specified. Skipping.\n");

		else

			mon->access_ev_id = event_id;



		ret = of_property_read_u32(dev->of_node, "qcom,wb-ev",

					   &event_id);

		if (ret)

			dev_dbg(dev, "WB event not specified. Skipping.\n");

		else

			mon->wb_ev_id = event_id;



		if (mon->wb_ev_id && mon->access_ev_id) {

			mon->access_ev =

				devm_kzalloc(dev, num_cpus *

					     sizeof(*mon->access_ev),

					     GFP_KERNEL);

			if (!mon->access_ev) {

				ret = -ENOMEM;

				goto unlock_out;

			}



			mon->wb_ev =

				devm_kzalloc(dev, num_cpus *

					     sizeof(*mon->wb_ev), GFP_KERNEL);

			if (!mon->wb_ev) {

				ret = -ENOMEM;

				goto unlock_out;

			}

		}



		ret = register_memlat(dev, hw);

	}

drivers/devfreq/governor_memlat.c

+16 −5
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ 
struct memlat_node {

	unsigned int ratio_ceil;

	unsigned int stall_floor;

	unsigned int wb_pct_thres;

	unsigned int wb_filter_ratio;

	bool mon_started;

	bool already_zero;

	struct list_head list;
@@ -292,11 +294,14 @@ static int devfreq_memlat_get_freq(struct devfreq *df, 
					hw->core_stats[i].inst_count,

					hw->core_stats[i].mem_count,

					hw->core_stats[i].freq,

					hw->core_stats[i].stall_pct, ratio);



		if (ratio <= node->ratio_ceil

		    && hw->core_stats[i].stall_pct >= node->stall_floor

		    && hw->core_stats[i].freq > max_freq) {

					hw->core_stats[i].stall_pct,

					hw->core_stats[i].wb_pct, ratio);



		if (((ratio <= node->ratio_ceil

		      && hw->core_stats[i].stall_pct >= node->stall_floor) ||

		      (hw->core_stats[i].wb_pct >= node->wb_pct_thres

		      && ratio <= node->wb_filter_ratio))

		      && (hw->core_stats[i].freq > max_freq)) {

			lat_dev = i;

			max_freq = hw->core_stats[i].freq;

		}
@@ -322,10 +327,14 @@ static int devfreq_memlat_get_freq(struct devfreq *df, 


gov_attr(ratio_ceil, 1U, 20000U);

gov_attr(stall_floor, 0U, 100U);

gov_attr(wb_pct_thres, 0U, 100U);

gov_attr(wb_filter_ratio, 0U, 50000U);



static struct attribute *memlat_dev_attr[] = {

	&dev_attr_ratio_ceil.attr,

	&dev_attr_stall_floor.attr,

	&dev_attr_wb_pct_thres.attr,

	&dev_attr_wb_filter_ratio.attr,

	&dev_attr_freq_map.attr,

	NULL,

};
@@ -488,6 +497,8 @@ static struct memlat_node *register_common(struct device *dev, 
		return ERR_PTR(-ENOMEM);



	node->ratio_ceil = 10;

	node->wb_pct_thres = 100;

	node->wb_filter_ratio = 25000;

	node->hw = hw;



	if (hw->get_child_of_node) {

drivers/devfreq/governor_memlat.h

+4 −0
Original line number Diff line number Diff line
@@ -15,6 +15,9 @@ 
 * @mem_count:			Number of memory accesses made.

 * @freq:			Effective frequency of the device in the

 *				last interval.

 * @wb_pct:			The ratio of writebacks to accesses. Used as an

 *				indirect way to identify memory latency due to

 *				snoop activity.

 */

struct dev_stats {

	int id;
@@ -22,6 +25,7 @@ struct dev_stats { 
	unsigned long mem_count;

	unsigned long freq;

	unsigned long stall_pct;

	unsigned long wb_pct;

};



struct core_dev_map {

include/trace/events/power.h

+6 −4
Original line number Diff line number Diff line
@@ -730,12 +730,11 @@ TRACE_EVENT(cache_hwmon_update, 
);



TRACE_EVENT(memlat_dev_meas,



	TP_PROTO(const char *name, unsigned int dev_id, unsigned long inst,

		 unsigned long mem, unsigned long freq, unsigned int stall,

		 unsigned int ratio),

		 unsigned int wb, unsigned int ratio),



	TP_ARGS(name, dev_id, inst, mem, freq, stall, ratio),

	TP_ARGS(name, dev_id, inst, mem, freq, stall, wb, ratio),



	TP_STRUCT__entry(

		__string(name, name)
@@ -744,6 +743,7 @@ TRACE_EVENT(memlat_dev_meas, 
		__field(unsigned long, mem)

		__field(unsigned long, freq)

		__field(unsigned int, stall)

		__field(unsigned int, wb)

		__field(unsigned int, ratio)

	),
@@ -754,16 +754,18 @@ TRACE_EVENT(memlat_dev_meas, 
		__entry->mem = mem;

		__entry->freq = freq;

		__entry->stall = stall;

		__entry->wb = wb;

		__entry->ratio = ratio;

	),



	TP_printk("dev: %s, id=%u, inst=%lu, mem=%lu, freq=%lu, stall=%u, ratio=%u",

	TP_printk("dev: %s, id=%u, inst=%lu, mem=%lu, freq=%lu, stall=%u, wb=%u, ratio=%u",

		__get_str(name),

		__entry->dev_id,

		__entry->inst,

		__entry->mem,

		__entry->freq,

		__entry->stall,

		__entry->wb,

		__entry->ratio)

);