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PM / devfreq: memlat: Add writeback percentage as a lat condition

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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: Santosh Mardi <gsantosh@codeaurora.org>
This commit is contained in:
Santosh Mardi 2020-07-14 08:50:33 +05:30
parent bd0cb90137
commit a4ff536215
4 changed files with 104 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

75
drivers/devfreq/arm-memlat-mon.c
View File

@ -68,8 +68,20 @@ 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.
@ -81,8 +93,12 @@ 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;
@ -208,6 +224,10 @@ static void update_counts(struct memlat_cpu_grp *cpu_grp)
cpu - cpumask_first(&mon->cpus);
cpu_grp->read_event_cpu = cpu;
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]);
}
cpu_grp->read_event_cpu = -1;
}
}
@ -238,6 +258,13 @@ 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;
@ -581,6 +608,18 @@ static int start_hwmon(struct memlat_hwmon *hw)
mon->miss_ev_id, attr);
if (ret < 0)
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;
}
}
}
@ -624,6 +663,7 @@ 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) {
@ -894,6 +934,8 @@ 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 =
@ -914,6 +956,39 @@ 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);
}

23
drivers/devfreq/governor_memlat.c
View File

@ -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;
@ -296,11 +298,14 @@ 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);
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].freq > max_freq) {
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;
}
@ -330,11 +335,19 @@ static DEVICE_ATTR_RW(ratio_ceil);
show_attr(stall_floor);
store_attr(stall_floor, 0U, 100U);
static DEVICE_ATTR_RW(stall_floor);
show_attr(wb_pct_thres);
store_attr(wb_pct_thres, 0U, 100U);
static DEVICE_ATTR_RW(wb_pct_thres);
show_attr(wb_filter_ratio);
store_attr(wb_filter_ratio, 0U, 50000U);
static DEVICE_ATTR_RW(wb_filter_ratio);
static struct attribute *memlat_dev_attr[] = {
&dev_attr_ratio_ceil.attr,
&dev_attr_stall_floor.attr,
&dev_attr_freq_map.attr,
&dev_attr_wb_pct_thres.attr,
&dev_attr_wb_filter_ratio.attr,
NULL,
};
@ -495,6 +508,8 @@ 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)

4
drivers/devfreq/governor_memlat.h
View File

@ -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 {

9
include/trace/events/power.h
View File

@ -670,9 +670,9 @@ 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)
@ -681,6 +681,7 @@ 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)
),
@ -691,16 +692,18 @@ 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)
);