For MBM, since we report total bytes for the duration the perf counts,
we need to keep the total bytes counted every time we loose an RMID.
Introduce rc_count(recycle count) per event
keep this history count(all bytes counted before the current RMID).
If we do not keep this count separately then we may end up sending a
count that may be less than the previous count during -I perf stat
option which leads to negative numbers being reported in the perf. This
happens say when we counted a greater amount with RMID1 and then
counted lesser with RMID2, and if user checks counts in interval mode
after RMID1 and then again after RMID2.
Signed-off-by: Vikas Shivappa <vikas.shiva...@linux.intel.com>
---
arch/x86/events/intel/cqm.c | 40 +++++++++++++++++++++++++++++++++++++---
include/linux/perf_event.h | 1 +
2 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 8dfba39..e679c39 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -479,6 +479,16 @@ static void cqm_mask_call(struct rmid_read *rr)
on_each_cpu_mask(&cqm_cpumask, __intel_cqm_event_count, rr, 1);
}
+static inline void mbm_set_rccount(
+ struct perf_event *event, struct rmid_read *rr)
+{
+ u64 tmpval;
+
+ tmpval = local64_read(&event->hw.rc_count) + atomic64_read(&rr->value);
+ local64_set(&event->hw.rc_count, tmpval);
+ local64_set(&event->count, tmpval);
+}
+
/*
* Exchange the RMID of a group of events.
*/
@@ -493,12 +503,19 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group,
u32 rmid)
/*
* If our RMID is being deallocated, perform a read now.
+ * For mbm, we need to store the bytes that were counted till now
+ * separately.
*/
if (__rmid_valid(old_rmid) && !__rmid_valid(rmid)) {
rr = __init_rr(old_rmid, group->attr.config, 0);
cqm_mask_call(&rr);
- local64_set(&group->count, atomic64_read(&rr.value));
+
+ if (is_mbm_event(group->attr.config))
+ mbm_set_rccount(group, &rr);
+ else
+ local64_set(&group->count, atomic64_read(&rr.value));
+
list_for_each_entry(event, head, hw.cqm_group_entry) {
if (event->hw.is_group_event) {
@@ -506,6 +523,9 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group,
u32 rmid)
rr = __init_rr(old_rmid, evttype, 0);
cqm_mask_call(&rr);
+ if (is_mbm_event(event->attr.config))
+ mbm_set_rccount(event, &rr);
+ else
local64_set(&event->count,
atomic64_read(&rr.value));
}
@@ -1194,6 +1214,7 @@ static u64 intel_cqm_event_count(struct perf_event *event)
{
unsigned long flags;
struct rmid_read rr = __init_rr(-1, event->attr.config, 0);
+ u64 tmpval;
/*
* We only need to worry about task events. System-wide events
@@ -1235,6 +1256,11 @@ static u64 intel_cqm_event_count(struct perf_event
*event)
* busying performing the IPI calls. It's therefore necessary to
* check @event's RMID afterwards, and if it has changed,
* discard the result of the read.
+ *
+ * For MBM events, we are reading the total bytes and not
+ * a snapshot. Hence if the RMID was recycled for the duration
+ * we will be adding the rc_count which keeps the historical count
+ * of old RMIDs that were used.
*/
rr.rmid = ACCESS_ONCE(event->hw.cqm_rmid);
@@ -1244,8 +1270,16 @@ static u64 intel_cqm_event_count(struct perf_event
*event)
cqm_mask_call(&rr);
raw_spin_lock_irqsave(&cache_lock, flags);
- if (event->hw.cqm_rmid == rr.rmid)
- local64_set(&event->count, atomic64_read(&rr.value));
+ 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_set(&event->count, tmpval);
+ } else {
+ local64_set(&event->count, atomic64_read(&rr.value));
+ }
+ }
raw_spin_unlock_irqrestore(&cache_lock, flags);
out:
return __perf_event_count(event);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f291275..ec7772a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -122,6 +122,7 @@ struct hw_perf_event {
int cqm_state;
u32 cqm_rmid;
int is_group_event;
+ local64_t rc_count;
struct list_head cqm_events_entry;
struct list_head cqm_groups_entry;
struct list_head cqm_group_entry;
--
1.9.1
