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Date: Tue, 22 Jun 2021 17:39:12 +0200
From: Jiri Olsa <jolsa@...hat.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: lkml <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Michael Petlan <mpetlan@...hat.com>,
Ian Rogers <irogers@...gle.com>
Subject: [PATCH 04/10] perf: Add new read_format bit to read lost events
It's now possible to retrieve lost stats by read
syscall on events.
Adding PERF_FORMAT_LOST read_format bit to get the
value of lost events through the read syscall.
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
include/linux/perf_event.h | 1 +
include/uapi/linux/perf_event.h | 5 ++++-
kernel/events/core.c | 21 ++++++++++++++++++---
kernel/events/ring_buffer.c | 3 +++
4 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 5110a998f59b..209c66a01797 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -670,6 +670,7 @@ struct perf_event {
local64_t count;
atomic64_t child_count;
local64_t build_id_faults;
+ local64_t lost;
/*
* These are the total time in nanoseconds that the event
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 2424ba7f95fb..e742c8f43a18 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -300,6 +300,7 @@ enum {
* { u64 time_running; } && PERF_FORMAT_TOTAL_TIME_RUNNING
* { u64 id; } && PERF_FORMAT_ID
* { u64 build_id_faults; } && PERF_FORMAT_BUILD_ID_FAULTS
+ * { u64 lost; } && PERF_FORMAT_LOST
* } && !PERF_FORMAT_GROUP
*
* { u64 nr;
@@ -308,6 +309,7 @@ enum {
* { u64 value;
* { u64 id; } && PERF_FORMAT_ID
* { u64 build_id_faults; } && PERF_FORMAT_BUILD_ID_FAULTS
+ * { u64 lost; } && PERF_FORMAT_LOST
* } cntr[nr];
* } && PERF_FORMAT_GROUP
* };
@@ -318,8 +320,9 @@ enum perf_event_read_format {
PERF_FORMAT_ID = 1U << 2,
PERF_FORMAT_GROUP = 1U << 3,
PERF_FORMAT_BUILD_ID_FAULTS = 1U << 4,
+ PERF_FORMAT_LOST = 1U << 5,
- PERF_FORMAT_MAX = 1U << 5, /* non-ABI */
+ PERF_FORMAT_MAX = 1U << 6, /* non-ABI */
};
#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f3cd06012115..ba02ce9e9134 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1843,6 +1843,9 @@ static void __perf_event_read_size(struct perf_event *event, int nr_siblings)
if (event->attr.read_format & PERF_FORMAT_BUILD_ID_FAULTS)
entry += sizeof(u64);
+ if (event->attr.read_format & PERF_FORMAT_LOST)
+ entry += sizeof(u64);
+
if (event->attr.read_format & PERF_FORMAT_GROUP) {
nr += nr_siblings;
size += sizeof(u64);
@@ -5252,6 +5255,8 @@ static int __perf_read_group_add(struct perf_event *leader,
values[n++] = primary_event_id(leader);
if (read_format & PERF_FORMAT_BUILD_ID_FAULTS)
values[n++] = local64_read(&leader->build_id_faults);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = local64_read(&leader->lost);
for_each_sibling_event(sub, leader) {
values[n++] += perf_event_count(sub);
@@ -5259,6 +5264,8 @@ static int __perf_read_group_add(struct perf_event *leader,
values[n++] = primary_event_id(sub);
if (read_format & PERF_FORMAT_BUILD_ID_FAULTS)
values[n++] = local64_read(&sub->build_id_faults);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = local64_read(&sub->lost);
}
raw_spin_unlock_irqrestore(&ctx->lock, flags);
@@ -5315,7 +5322,7 @@ static int perf_read_one(struct perf_event *event,
u64 read_format, char __user *buf)
{
u64 enabled, running;
- u64 values[5];
+ u64 values[6];
int n = 0;
values[n++] = __perf_event_read_value(event, &enabled, &running);
@@ -5327,6 +5334,8 @@ static int perf_read_one(struct perf_event *event,
values[n++] = primary_event_id(event);
if (read_format & PERF_FORMAT_BUILD_ID_FAULTS)
values[n++] = local64_read(&event->build_id_faults);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = local64_read(&event->lost);
if (copy_to_user(buf, values, n * sizeof(u64)))
return -EFAULT;
@@ -6829,7 +6838,7 @@ static void perf_output_read_one(struct perf_output_handle *handle,
u64 enabled, u64 running)
{
u64 read_format = event->attr.read_format;
- u64 values[5];
+ u64 values[6];
int n = 0;
values[n++] = perf_event_count(event);
@@ -6845,6 +6854,8 @@ static void perf_output_read_one(struct perf_output_handle *handle,
values[n++] = primary_event_id(event);
if (read_format & PERF_FORMAT_BUILD_ID_FAULTS)
values[n++] = local64_read(&event->build_id_faults);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = local64_read(&event->lost);
__output_copy(handle, values, n * sizeof(u64));
}
@@ -6855,7 +6866,7 @@ static void perf_output_read_group(struct perf_output_handle *handle,
{
struct perf_event *leader = event->group_leader, *sub;
u64 read_format = event->attr.read_format;
- u64 values[6];
+ u64 values[7];
int n = 0;
values[n++] = 1 + leader->nr_siblings;
@@ -6875,6 +6886,8 @@ static void perf_output_read_group(struct perf_output_handle *handle,
values[n++] = primary_event_id(leader);
if (read_format & PERF_FORMAT_BUILD_ID_FAULTS)
values[n++] = local64_read(&leader->build_id_faults);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = local64_read(&leader->lost);
__output_copy(handle, values, n * sizeof(u64));
@@ -6890,6 +6903,8 @@ static void perf_output_read_group(struct perf_output_handle *handle,
values[n++] = primary_event_id(sub);
if (read_format & PERF_FORMAT_BUILD_ID_FAULTS)
values[n++] = local64_read(&sub->build_id_faults);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = local64_read(&sub->lost);
__output_copy(handle, values, n * sizeof(u64));
}
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 52868716ec35..51738bc7cf44 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -248,6 +248,9 @@ __perf_output_begin(struct perf_output_handle *handle,
perf_event_header__init_id(&lost_event.header, data, event);
perf_output_put(handle, lost_event);
perf_event__output_id_sample(event, handle, data);
+
+ /* Keep track of lost events in event for PERF_FORMAT_LOST */
+ local64_add(lost_event.lost, &event->lost);
}
return 0;
--
2.31.1
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