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Message-ID: <165640059260.4207.6165560170010032582.tip-bot2@tip-bot2>
Date: Tue, 28 Jun 2022 07:16:32 -0000
From: "tip-bot2 for Namhyung Kim" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Namhyung Kim <namhyung@...nel.org>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf/core: Add a new read format to get a number of
lost samples
The following commit has been merged into the perf/core branch of tip:
Commit-ID: 119a784c81270eb88e573174ed2209225d646656
Gitweb: https://git.kernel.org/tip/119a784c81270eb88e573174ed2209225d646656
Author: Namhyung Kim <namhyung@...nel.org>
AuthorDate: Thu, 16 Jun 2022 11:06:23 -07:00
Committer: Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 28 Jun 2022 09:08:31 +02:00
perf/core: Add a new read format to get a number of lost samples
Sometimes we want to know an accurate number of samples even if it's
lost. Currenlty PERF_RECORD_LOST is generated for a ring-buffer which
might be shared with other events. So it's hard to know per-event
lost count.
Add event->lost_samples field and PERF_FORMAT_LOST to retrieve it from
userspace.
Original-patch-by: Jiri Olsa <jolsa@...hat.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20220616180623.1358843-1-namhyung@kernel.org
---
include/linux/perf_event.h | 2 ++
include/uapi/linux/perf_event.h | 5 ++++-
kernel/events/core.c | 21 ++++++++++++++++++---
kernel/events/ring_buffer.c | 5 ++++-
4 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index da75956..ee8b9ec 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -759,6 +759,8 @@ struct perf_event {
struct pid_namespace *ns;
u64 id;
+ atomic64_t lost_samples;
+
u64 (*clock)(void);
perf_overflow_handler_t overflow_handler;
void *overflow_handler_context;
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index d37629d..0474ee3 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -301,6 +301,7 @@ enum {
* { u64 time_enabled; } && PERF_FORMAT_TOTAL_TIME_ENABLED
* { u64 time_running; } && PERF_FORMAT_TOTAL_TIME_RUNNING
* { u64 id; } && PERF_FORMAT_ID
+ * { u64 lost; } && PERF_FORMAT_LOST
* } && !PERF_FORMAT_GROUP
*
* { u64 nr;
@@ -308,6 +309,7 @@ enum {
* { u64 time_running; } && PERF_FORMAT_TOTAL_TIME_RUNNING
* { u64 value;
* { u64 id; } && PERF_FORMAT_ID
+ * { u64 lost; } && PERF_FORMAT_LOST
* } cntr[nr];
* } && PERF_FORMAT_GROUP
* };
@@ -317,8 +319,9 @@ enum perf_event_read_format {
PERF_FORMAT_TOTAL_TIME_RUNNING = 1U << 1,
PERF_FORMAT_ID = 1U << 2,
PERF_FORMAT_GROUP = 1U << 3,
+ PERF_FORMAT_LOST = 1U << 4,
- PERF_FORMAT_MAX = 1U << 4, /* non-ABI */
+ PERF_FORMAT_MAX = 1U << 5, /* 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 80782cd..4d8c335 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1819,6 +1819,9 @@ static void __perf_event_read_size(struct perf_event *event, int nr_siblings)
if (event->attr.read_format & PERF_FORMAT_ID)
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);
@@ -5260,11 +5263,15 @@ static int __perf_read_group_add(struct perf_event *leader,
values[n++] += perf_event_count(leader);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(leader);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = atomic64_read(&leader->lost_samples);
for_each_sibling_event(sub, leader) {
values[n++] += perf_event_count(sub);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(sub);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = atomic64_read(&sub->lost_samples);
}
raw_spin_unlock_irqrestore(&ctx->lock, flags);
@@ -5321,7 +5328,7 @@ static int perf_read_one(struct perf_event *event,
u64 read_format, char __user *buf)
{
u64 enabled, running;
- u64 values[4];
+ u64 values[5];
int n = 0;
values[n++] = __perf_event_read_value(event, &enabled, &running);
@@ -5331,6 +5338,8 @@ static int perf_read_one(struct perf_event *event,
values[n++] = running;
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(event);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = atomic64_read(&event->lost_samples);
if (copy_to_user(buf, values, n * sizeof(u64)))
return -EFAULT;
@@ -6858,7 +6867,7 @@ static void perf_output_read_one(struct perf_output_handle *handle,
u64 enabled, u64 running)
{
u64 read_format = event->attr.read_format;
- u64 values[4];
+ u64 values[5];
int n = 0;
values[n++] = perf_event_count(event);
@@ -6872,6 +6881,8 @@ static void perf_output_read_one(struct perf_output_handle *handle,
}
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(event);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = atomic64_read(&event->lost_samples);
__output_copy(handle, values, n * sizeof(u64));
}
@@ -6882,7 +6893,7 @@ 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[5];
+ u64 values[6];
int n = 0;
values[n++] = 1 + leader->nr_siblings;
@@ -6900,6 +6911,8 @@ static void perf_output_read_group(struct perf_output_handle *handle,
values[n++] = perf_event_count(leader);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(leader);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = atomic64_read(&leader->lost_samples);
__output_copy(handle, values, n * sizeof(u64));
@@ -6913,6 +6926,8 @@ static void perf_output_read_group(struct perf_output_handle *handle,
values[n++] = perf_event_count(sub);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(sub);
+ if (read_format & PERF_FORMAT_LOST)
+ values[n++] = atomic64_read(&sub->lost_samples);
__output_copy(handle, values, n * sizeof(u64));
}
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index fb35b92..7261320 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -172,8 +172,10 @@ __perf_output_begin(struct perf_output_handle *handle,
goto out;
if (unlikely(rb->paused)) {
- if (rb->nr_pages)
+ if (rb->nr_pages) {
local_inc(&rb->lost);
+ atomic64_inc(&event->lost_samples);
+ }
goto out;
}
@@ -254,6 +256,7 @@ __perf_output_begin(struct perf_output_handle *handle,
fail:
local_inc(&rb->lost);
+ atomic64_inc(&event->lost_samples);
perf_output_put_handle(handle);
out:
rcu_read_unlock();
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