[PATCH 3/4] perf/x86/mbm: Fix mbm counting when RMIDs are reused
From: Vikas Shivappa
Date: Fri Apr 22 2016 - 20:28:18 EST
When multiple instances of perf reuse RMID, then we need to start
counting for each instance rather than reporting the current RMID count.
This patch adds a st_count(start count) per event to track the same.
Signed-off-by: Vikas Shivappa <vikas.shivappa@xxxxxxxxxxxxxxx>
---
arch/x86/events/intel/cqm.c | 71 ++++++++++++++++++++++++++++++++++++++++++---
include/linux/perf_event.h | 1 +
2 files changed, 68 insertions(+), 4 deletions(-)
diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index e679c39..7328b73 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -484,8 +484,18 @@ static inline void mbm_set_rccount(
{
u64 tmpval;
- tmpval = local64_read(&event->hw.rc_count) + atomic64_read(&rr->value);
+ tmpval = local64_read(&event->hw.rc_count) + atomic64_read(&rr->value) -
+ local64_read(&event->hw.st_count);
+
local64_set(&event->hw.rc_count, tmpval);
+
+ /*
+ * The st_count(start count) is meant to store the starting bytes
+ * for an event which is reusing an RMID which already
+ * had bytes measured.Once we start using the rc_count
+ * to keep the history bytes, reset the start bytes.
+ */
+ local64_set(&event->hw.st_count, 0UL);
local64_set(&event->count, tmpval);
}
@@ -1025,6 +1035,58 @@ static void init_mbm_sample(u32 rmid, u32 evt_type)
on_each_cpu_mask(&cqm_cpumask, __intel_mbm_event_init, &rr, 1);
}
+static inline bool first_event_ingroup(struct perf_event *group,
+ struct perf_event *event)
+{
+ struct list_head *head = &group->hw.cqm_group_entry;
+ u32 evt_type = event->attr.config;
+
+ if (evt_type == group->attr.config)
+ return false;
+ list_for_each_entry(event, head, hw.cqm_group_entry) {
+ if (evt_type == event->attr.config)
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * mbm_setup_event - Does mbm specific count initialization
+ * when multiple events share RMID.
+ *
+ * If this is the first mbm event using the RMID, then initialize
+ * the total_bytes in the RMID and prev_count.
+ * else only initialize the start count of the event which is the current
+ * count of the RMID.
+ * In other words if the RMID has say counted 100MB till now because
+ * other event was already using it, we start
+ * from zero for our new event. Because after 1s if user checks the count,
+ * we need to report for the 1s duration and not the entire duration the
+ * RMID was being counted.
+*/
+static inline void mbm_setup_event(u32 rmid, struct perf_event *group,
+ struct perf_event *event)
+{
+ u32 evt_type = event->attr.config;
+ struct rmid_read rr;
+
+ if (first_event_ingroup(group, event)) {
+ init_mbm_sample(rmid, evt_type);
+ } else {
+ rr = __init_rr(rmid, evt_type, 0);
+ cqm_mask_call(&rr);
+ local64_set(&event->hw.st_count, atomic64_read(&rr.value));
+ }
+}
+
+static inline void mbm_setup_event_init(struct perf_event *event)
+{
+ event->hw.is_group_event = false;
+ local64_set(&event->hw.rc_count, 0UL);
+ local64_set(&event->hw.st_count, 0UL);
+}
+
/*
* Find a group and setup RMID.
*
@@ -1037,7 +1099,7 @@ static void intel_cqm_setup_event(struct perf_event *event,
bool conflict = false;
u32 rmid;
- event->hw.is_group_event = false;
+ mbm_setup_event_init(event);
list_for_each_entry(iter, &cache_groups, hw.cqm_groups_entry) {
rmid = iter->hw.cqm_rmid;
@@ -1046,7 +1108,7 @@ static void intel_cqm_setup_event(struct perf_event *event,
event->hw.cqm_rmid = rmid;
*group = iter;
if (is_mbm_event(event->attr.config) && __rmid_valid(rmid))
- init_mbm_sample(rmid, event->attr.config);
+ mbm_setup_event(rmid, iter, event);
return;
}
@@ -1273,7 +1335,8 @@ static u64 intel_cqm_event_count(struct perf_event *event)
if (event->hw.cqm_rmid == rr.rmid) {
if (is_mbm_event(event->attr.config)) {
tmpval = atomic64_read(&rr.value) +
- local64_read(&event->hw.rc_count);
+ local64_read(&event->hw.rc_count) -
+ local64_read(&event->hw.st_count);
local64_set(&event->count, tmpval);
} else {
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ec7772a..44a7f0c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -123,6 +123,7 @@ struct hw_perf_event {
u32 cqm_rmid;
int is_group_event;
local64_t rc_count;
+ local64_t st_count;
struct list_head cqm_events_entry;
struct list_head cqm_groups_entry;
struct list_head cqm_group_entry;
--
1.9.1