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Date: Wed, 18 May 2022 15:47:24 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Andi Kleen <ak@...ux.intel.com>,
Ian Rogers <irogers@...gle.com>,
Song Liu <songliubraving@...com>, Hao Luo <haoluo@...gle.com>,
Milian Wolff <milian.wolff@...b.com>, bpf@...r.kernel.org,
linux-perf-users@...r.kernel.org,
Blake Jones <blakejones@...gle.com>
Subject: [PATCH 5/6] perf record: Add cgroup support for off-cpu profiling
This covers two different use cases. The first one is cgroup
filtering given by -G/--cgroup option which controls the off-cpu
profiling for tasks in the given cgroups only.
The other use case is cgroup sampling which is enabled by
--all-cgroups option and it adds PERF_SAMPLE_CGROUP to the sample_type
to set the cgroup id of the task in the sample data.
Example output.
$ sudo perf record -a --off-cpu --all-cgroups sleep 1
$ sudo perf report --stdio -s comm,cgroup --call-graph=no
...
# Samples: 144 of event 'offcpu-time'
# Event count (approx.): 48452045427
#
# Children Self Command Cgroup
# ........ ........ ............... ..........................................
#
61.57% 5.60% Chrome_ChildIOT /user.slice/user-657345.slice/user@...345.service/app.slice/...
29.51% 7.38% Web Content /user.slice/user-657345.slice/user@...345.service/app.slice/...
17.48% 1.59% Chrome_IOThread /user.slice/user-657345.slice/user@...345.service/app.slice/...
16.48% 4.12% pipewire-pulse /user.slice/user-657345.slice/user@...345.service/session.slice/...
14.48% 2.07% perf /user.slice/user-657345.slice/user@...345.service/app.slice/...
14.30% 7.15% CompositorTileW /user.slice/user-657345.slice/user@...345.service/app.slice/...
13.33% 6.67% Timer /user.slice/user-657345.slice/user@...345.service/app.slice/...
...
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/builtin-record.c | 2 +-
tools/perf/util/bpf_off_cpu.c | 48 ++++++++++++++++++++++++--
tools/perf/util/bpf_skel/off_cpu.bpf.c | 33 ++++++++++++++++++
tools/perf/util/off_cpu.h | 7 ++--
4 files changed, 85 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7f60d2eac0b4..77fa21c2c69f 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -907,7 +907,7 @@ static int record__config_text_poke(struct evlist *evlist)
static int record__config_off_cpu(struct record *rec)
{
- return off_cpu_prepare(rec->evlist, &rec->opts.target);
+ return off_cpu_prepare(rec->evlist, &rec->opts.target, &rec->opts);
}
static bool record__kcore_readable(struct machine *machine)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 874856c55101..b73e84a02264 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -5,10 +5,12 @@
#include "util/evlist.h"
#include "util/off_cpu.h"
#include "util/perf-hooks.h"
+#include "util/record.h"
#include "util/session.h"
#include "util/target.h"
#include "util/cpumap.h"
#include "util/thread_map.h"
+#include "util/cgroup.h"
#include <bpf/bpf.h>
#include "bpf_skel/off_cpu.skel.h"
@@ -24,6 +26,7 @@ struct off_cpu_key {
u32 tgid;
u32 stack_id;
u32 state;
+ u64 cgroup_id;
};
union off_cpu_data {
@@ -116,10 +119,11 @@ static void check_sched_switch_args(void)
}
}
-int off_cpu_prepare(struct evlist *evlist, struct target *target)
+int off_cpu_prepare(struct evlist *evlist, struct target *target,
+ struct record_opts *opts)
{
int err, fd, i;
- int ncpus = 1, ntasks = 1;
+ int ncpus = 1, ntasks = 1, ncgrps = 1;
if (off_cpu_config(evlist) < 0) {
pr_err("Failed to config off-cpu BPF event\n");
@@ -143,6 +147,21 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target)
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
}
+ if (evlist__first(evlist)->cgrp) {
+ ncgrps = evlist->core.nr_entries - 1; /* excluding a dummy */
+ bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps);
+
+ if (!cgroup_is_v2("perf_event"))
+ skel->rodata->uses_cgroup_v1 = true;
+ }
+
+ if (opts->record_cgroup) {
+ skel->rodata->needs_cgroup = true;
+
+ if (!cgroup_is_v2("perf_event"))
+ skel->rodata->uses_cgroup_v1 = true;
+ }
+
set_max_rlimit();
check_sched_switch_args();
@@ -178,6 +197,29 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target)
}
}
+ if (evlist__first(evlist)->cgrp) {
+ struct evsel *evsel;
+ u8 val = 1;
+
+ skel->bss->has_cgroup = 1;
+ fd = bpf_map__fd(skel->maps.cgroup_filter);
+
+ evlist__for_each_entry(evlist, evsel) {
+ struct cgroup *cgrp = evsel->cgrp;
+
+ if (cgrp == NULL)
+ continue;
+
+ if (!cgrp->id && read_cgroup_id(cgrp) < 0) {
+ pr_err("Failed to read cgroup id of %s\n",
+ cgrp->name);
+ goto out;
+ }
+
+ bpf_map_update_elem(fd, &cgrp->id, &val, BPF_ANY);
+ }
+ }
+
err = off_cpu_bpf__attach(skel);
if (err) {
pr_err("Failed to attach off-cpu BPF skeleton\n");
@@ -275,6 +317,8 @@ int off_cpu_write(struct perf_session *session)
/* calculate sample callchain data array length */
n += len + 2;
}
+ if (sample_type & PERF_SAMPLE_CGROUP)
+ data.array[n++] = key.cgroup_id;
/* TODO: handle more sample types */
size = n * sizeof(u64);
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index 986d7db6e75d..792ae2847080 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -26,6 +26,7 @@ struct offcpu_key {
__u32 tgid;
__u32 stack_id;
__u32 state;
+ __u64 cgroup_id;
};
struct {
@@ -63,6 +64,13 @@ struct {
__uint(max_entries, 1);
} task_filter SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(key_size, sizeof(__u64));
+ __uint(value_size, sizeof(__u8));
+ __uint(max_entries, 1);
+} cgroup_filter SEC(".maps");
+
/* old kernel task_struct definition */
struct task_struct___old {
long state;
@@ -71,8 +79,11 @@ struct task_struct___old {
int enabled = 0;
int has_cpu = 0;
int has_task = 0;
+int has_cgroup = 0;
const volatile bool has_prev_state = false;
+const volatile bool needs_cgroup = false;
+const volatile bool uses_cgroup_v1 = false;
/*
* Old kernel used to call it task_struct->state and now it's '__state'.
@@ -92,6 +103,18 @@ static inline int get_task_state(struct task_struct *t)
return BPF_CORE_READ(t_old, state);
}
+static inline __u64 get_cgroup_id(struct task_struct *t)
+{
+ struct cgroup *cgrp;
+
+ if (uses_cgroup_v1)
+ cgrp = BPF_CORE_READ(t, cgroups, subsys[perf_event_cgrp_id], cgroup);
+ else
+ cgrp = BPF_CORE_READ(t, cgroups, dfl_cgrp);
+
+ return BPF_CORE_READ(cgrp, kn, id);
+}
+
static inline int can_record(struct task_struct *t, int state)
{
/* kernel threads don't have user stack */
@@ -120,6 +143,15 @@ static inline int can_record(struct task_struct *t, int state)
return 0;
}
+ if (has_cgroup) {
+ __u8 *ok;
+ __u64 cgrp_id = get_cgroup_id(t);
+
+ ok = bpf_map_lookup_elem(&cgroup_filter, &cgrp_id);
+ if (!ok)
+ return 0;
+ }
+
return 1;
}
@@ -156,6 +188,7 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
.tgid = next->tgid,
.stack_id = pelem->stack_id,
.state = pelem->state,
+ .cgroup_id = needs_cgroup ? get_cgroup_id(next) : 0,
};
__u64 delta = ts - pelem->timestamp;
__u64 *total;
diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
index f47af0232e55..548008f74d42 100644
--- a/tools/perf/util/off_cpu.h
+++ b/tools/perf/util/off_cpu.h
@@ -4,15 +4,18 @@
struct evlist;
struct target;
struct perf_session;
+struct record_opts;
#define OFFCPU_EVENT "offcpu-time"
#ifdef HAVE_BPF_SKEL
-int off_cpu_prepare(struct evlist *evlist, struct target *target);
+int off_cpu_prepare(struct evlist *evlist, struct target *target,
+ struct record_opts *opts);
int off_cpu_write(struct perf_session *session);
#else
static inline int off_cpu_prepare(struct evlist *evlist __maybe_unused,
- struct target *target __maybe_unused)
+ struct target *target __maybe_unused,
+ struct record_opts *opts __maybe_unused)
{
return -1;
}
--
2.36.1.124.g0e6072fb45-goog
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