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Message-ID: <20240927202736.767941-6-howardchu95@gmail.com>
Date: Fri, 27 Sep 2024 13:27:33 -0700
From: Howard Chu <howardchu95@...il.com>
To: peterz@...radead.org
Cc: mingo@...hat.com,
acme@...nel.org,
namhyung@...nel.org,
mark.rutland@....com,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
kan.liang@...ux.intel.com,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
Howard Chu <howardchu95@...il.com>
Subject: [PATCH v6 5/8] perf record --off-cpu: Dump total off-cpu time at the end.
By setting a placeholder sample_type and then writing real data into
raw_data, we mimic the direct sample method to write data at the end.
Note that some data serve only as placeholders and will be overwritten
by the data in raw_data. Additionally, since the IP will be updated in
evsel__parse_sample(), there is no need to handle it in off_cpu_write().
Suggested-by: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Howard Chu <howardchu95@...il.com>
---
tools/perf/util/bpf_off_cpu.c | 116 +++++++++++++++++++++-------------
1 file changed, 72 insertions(+), 44 deletions(-)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index f7233a09ec77..2a1cfd7e0b09 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -138,12 +138,19 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
int ncpus = 1, ntasks = 1, ncgrps = 1;
struct strlist *pid_slist = NULL;
struct str_node *pos;
+ struct evsel *evsel;
if (off_cpu_config(evlist) < 0) {
pr_err("Failed to config off-cpu BPF event\n");
return -1;
}
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
+ if (evsel == NULL) {
+ pr_err("%s evsel not found\n", OFFCPU_EVENT);
+ return -1 ;
+ }
+
skel = off_cpu_bpf__open();
if (!skel) {
pr_err("Failed to open off-cpu BPF skeleton\n");
@@ -259,7 +266,6 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
if (evlist__first(evlist)->cgrp) {
- struct evsel *evsel;
u8 val = 1;
fd = bpf_map__fd(skel->maps.cgroup_filter);
@@ -280,6 +286,7 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
}
+ skel->bss->sample_type = OFFCPU_EMBEDDED_SAMPLE_TYPES;
skel->bss->offcpu_thresh = opts->off_cpu_thresh * 1000;
err = off_cpu_bpf__attach(skel);
@@ -305,7 +312,8 @@ int off_cpu_write(struct perf_session *session)
{
int bytes = 0, size;
int fd, stack;
- u64 sample_type, val, sid = 0;
+ u32 raw_size;
+ u64 sample_type_off_cpu, sample_type_bpf_output, val, sid = 0, tstamp = OFF_CPU_TIMESTAMP;
struct evsel *evsel;
struct perf_data_file *file = &session->data->file;
struct off_cpu_key prev, key;
@@ -315,7 +323,6 @@ int off_cpu_write(struct perf_session *session)
.misc = PERF_RECORD_MISC_USER,
},
};
- u64 tstamp = OFF_CPU_TIMESTAMP;
skel->bss->enabled = 0;
@@ -325,15 +332,10 @@ int off_cpu_write(struct perf_session *session)
return 0;
}
- sample_type = evsel->core.attr.sample_type;
-
- if (sample_type & ~OFFCPU_SAMPLE_TYPES) {
- pr_err("not supported sample type: %llx\n",
- (unsigned long long)sample_type);
- return -1;
- }
+ sample_type_off_cpu = OFFCPU_EMBEDDED_SAMPLE_TYPES;
+ sample_type_bpf_output = evsel->core.attr.sample_type;
- if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) {
+ if (sample_type_bpf_output & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) {
if (evsel->core.id)
sid = evsel->core.id[0];
}
@@ -344,49 +346,75 @@ int off_cpu_write(struct perf_session *session)
while (!bpf_map_get_next_key(fd, &prev, &key)) {
int n = 1; /* start from perf_event_header */
- int ip_pos = -1;
+ int i = 0; /* raw data index */
bpf_map_lookup_elem(fd, &key, &val);
- if (sample_type & PERF_SAMPLE_IDENTIFIER)
+ /*
+ * Zero-fill some of these fields first, they will be overwritten by the dummy
+ * embedded data (in raw_data) below, when parsing the samples. And because embedded
+ * data is in BPF output, perf script -F without bpf-output field will not work
+ * properly.
+ */
+ if (sample_type_bpf_output & PERF_SAMPLE_IDENTIFIER)
data.array[n++] = sid;
- if (sample_type & PERF_SAMPLE_IP) {
- ip_pos = n;
- data.array[n++] = 0; /* will be updated */
- }
- if (sample_type & PERF_SAMPLE_TID)
- data.array[n++] = (u64)key.pid << 32 | key.tgid;
- if (sample_type & PERF_SAMPLE_TIME)
- data.array[n++] = tstamp;
- if (sample_type & PERF_SAMPLE_ID)
- data.array[n++] = sid;
- if (sample_type & PERF_SAMPLE_CPU)
+ if (sample_type_bpf_output & PERF_SAMPLE_IP)
data.array[n++] = 0;
- if (sample_type & PERF_SAMPLE_PERIOD)
- data.array[n++] = val;
- if (sample_type & PERF_SAMPLE_CALLCHAIN) {
- int len = 0;
-
- /* data.array[n] is callchain->nr (updated later) */
- data.array[n + 1] = PERF_CONTEXT_USER;
- data.array[n + 2] = 0;
+ if (sample_type_bpf_output & PERF_SAMPLE_TID)
+ data.array[n++] = 0;
+ if (sample_type_bpf_output & PERF_SAMPLE_TIME)
+ data.array[n++] = tstamp; /* we won't overwrite time */
+ if (sample_type_bpf_output & PERF_SAMPLE_CPU)
+ data.array[n++] = 0;
+ if (sample_type_bpf_output & PERF_SAMPLE_PERIOD)
+ data.array[n++] = 0;
+ if (sample_type_bpf_output & PERF_SAMPLE_RAW) {
+ /*
+ * the format of raw data is as follows:
+ *
+ * [ size ][ data ]
+ * [ data ]
+ * [ data ]
+ * [ data ]
+ * [ data ][ empty]
+ *
+ */
+ if (sample_type_off_cpu & PERF_SAMPLE_TID)
+ off_cpu_raw_data[i++] = (u64)key.pid << 32 | key.tgid;
+ if (sample_type_off_cpu & PERF_SAMPLE_PERIOD)
+ off_cpu_raw_data[i++] = val;
+ if (sample_type_off_cpu & PERF_SAMPLE_CALLCHAIN) {
+ int len = 0;
+
+ /* off_cpu_raw_data[n] is callchain->nr (updated later) */
+ off_cpu_raw_data[i + 1] = PERF_CONTEXT_USER;
+ off_cpu_raw_data[i + 2] = 0;
+
+ bpf_map_lookup_elem(stack, &key.stack_id, &off_cpu_raw_data[i + 2]);
+ while (off_cpu_raw_data[i + 2 + len])
+ len++;
+
+ /* update length of callchain */
+ off_cpu_raw_data[i] = len + 1;
+
+ /* calculate sample callchain off_cpu_raw_data length */
+ i += len + 2;
+ }
+ if (sample_type_off_cpu & PERF_SAMPLE_CGROUP)
+ off_cpu_raw_data[i++] = key.cgroup_id;
- bpf_map_lookup_elem(stack, &key.stack_id, &data.array[n + 2]);
- while (data.array[n + 2 + len])
- len++;
+ raw_size = i * sizeof(u64) + sizeof(u32); /* 4 empty bytes for alignment */
- /* update length of callchain */
- data.array[n] = len + 1;
+ /* raw_size */
+ memcpy((void *)data.array + n * sizeof(u64), &raw_size, sizeof(raw_size));
- /* update sample ip with the first callchain entry */
- if (ip_pos >= 0)
- data.array[ip_pos] = data.array[n + 2];
+ /* raw_data */
+ memcpy((void *)data.array + n * sizeof(u64) + sizeof(u32), off_cpu_raw_data, i * sizeof(u64));
- /* calculate sample callchain data array length */
- n += len + 2;
+ n += i + 1;
}
- if (sample_type & PERF_SAMPLE_CGROUP)
- data.array[n++] = key.cgroup_id;
+ if (sample_type_bpf_output & PERF_SAMPLE_CGROUP)
+ data.array[n++] = 0;
size = n * sizeof(u64);
data.hdr.size = size;
--
2.43.0
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