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Message-Id: <20220422053401.208207-4-namhyung@kernel.org>
Date: Thu, 21 Apr 2022 22:34:00 -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>,
bpf@...r.kernel.org, linux-perf-users@...r.kernel.org,
Blake Jones <blakejones@...gle.com>
Subject: [PATCH 3/4] perf record: Implement basic filtering for off-cpu
It should honor cpu and task filtering with -a, -C or -p, -t options.
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/builtin-record.c | 2 +-
tools/perf/util/bpf_off_cpu.c | 78 +++++++++++++++++++++++---
tools/perf/util/bpf_skel/off_cpu.bpf.c | 52 +++++++++++++++--
3 files changed, 119 insertions(+), 13 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 3d24d528ba8e..592384e058c3 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);
+ return off_cpu_prepare(rec->evlist, &rec->opts.target);
}
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 1f87d2a9b86d..89f36229041d 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -6,6 +6,9 @@
#include "util/off_cpu.h"
#include "util/perf-hooks.h"
#include "util/session.h"
+#include "util/target.h"
+#include "util/cpumap.h"
+#include "util/thread_map.h"
#include <bpf/bpf.h>
#include "bpf_skel/off_cpu.skel.h"
@@ -57,8 +60,23 @@ static int off_cpu_config(struct evlist *evlist)
return 0;
}
-static void off_cpu_start(void *arg __maybe_unused)
+static void off_cpu_start(void *arg)
{
+ struct evlist *evlist = arg;
+
+ /* update task filter for the given workload */
+ if (!skel->bss->has_cpu && !skel->bss->has_task &&
+ perf_thread_map__pid(evlist->core.threads, 0) != -1) {
+ int fd;
+ u32 pid;
+ u8 val = 1;
+
+ skel->bss->has_task = 1;
+ fd = bpf_map__fd(skel->maps.task_filter);
+ pid = perf_thread_map__pid(evlist->core.threads, 0);
+ bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
+ }
+
skel->bss->enabled = 1;
}
@@ -68,31 +86,75 @@ static void off_cpu_finish(void *arg __maybe_unused)
off_cpu_bpf__destroy(skel);
}
-int off_cpu_prepare(struct evlist *evlist)
+int off_cpu_prepare(struct evlist *evlist, struct target *target)
{
- int err;
+ int err, fd, i;
+ int ncpus = 1, ntasks = 1;
if (off_cpu_config(evlist) < 0) {
pr_err("Failed to config off-cpu BPF event\n");
return -1;
}
- set_max_rlimit();
-
- skel = off_cpu_bpf__open_and_load();
+ skel = off_cpu_bpf__open();
if (!skel) {
pr_err("Failed to open off-cpu skeleton\n");
return -1;
}
+ /* don't need to set cpu filter for system-wide mode */
+ if (target->cpu_list) {
+ ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
+ bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
+ }
+
+ if (target__has_task(target)) {
+ ncpus = perf_thread_map__nr(evlist->core.threads);
+ bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+ }
+
+ set_max_rlimit();
+
+ err = off_cpu_bpf__load(skel);
+ if (err) {
+ pr_err("Failed to load off-cpu skeleton\n");
+ goto out;
+ }
+
+ if (target->cpu_list) {
+ u32 cpu;
+ u8 val = 1;
+
+ skel->bss->has_cpu = 1;
+ fd = bpf_map__fd(skel->maps.cpu_filter);
+
+ for (i = 0; i < ncpus; i++) {
+ cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
+ bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
+ }
+ }
+
+ if (target__has_task(target)) {
+ u32 pid;
+ u8 val = 1;
+
+ skel->bss->has_task = 1;
+ fd = bpf_map__fd(skel->maps.task_filter);
+
+ for (i = 0; i < ntasks; i++) {
+ pid = perf_thread_map__pid(evlist->core.threads, i);
+ bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
+ }
+ }
+
err = off_cpu_bpf__attach(skel);
if (err) {
pr_err("Failed to attach off-cpu skeleton\n");
goto out;
}
- if (perf_hooks__set_hook("record_start", off_cpu_start, NULL) ||
- perf_hooks__set_hook("record_end", off_cpu_finish, NULL)) {
+ if (perf_hooks__set_hook("record_start", off_cpu_start, evlist) ||
+ perf_hooks__set_hook("record_end", off_cpu_finish, evlist)) {
pr_err("Failed to attach off-cpu skeleton\n");
goto out;
}
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index 2bc6f7cc59ea..27425fe361e2 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -49,12 +49,28 @@ struct {
__uint(max_entries, MAX_ENTRIES);
} off_cpu SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u8));
+ __uint(max_entries, 1);
+} cpu_filter SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u8));
+ __uint(max_entries, 1);
+} task_filter SEC(".maps");
+
/* old kernel task_struct definition */
struct task_struct___old {
long state;
} __attribute__((preserve_access_index));
int enabled = 0;
+int has_cpu = 0;
+int has_task = 0;
/*
* recently task_struct->state renamed to __state so it made an incompatible
@@ -74,6 +90,37 @@ static inline int get_task_state(struct task_struct *t)
return BPF_CORE_READ(t_old, state);
}
+static inline int can_record(struct task_struct *t, int state)
+{
+ if (has_cpu) {
+ __u32 cpu = bpf_get_smp_processor_id();
+ __u8 *ok;
+
+ ok = bpf_map_lookup_elem(&cpu_filter, &cpu);
+ if (!ok)
+ return 0;
+ }
+
+ if (has_task) {
+ __u8 *ok;
+ __u32 pid = t->pid;
+
+ ok = bpf_map_lookup_elem(&task_filter, &pid);
+ if (!ok)
+ return 0;
+ }
+
+ /* kernel threads don't have user stack */
+ if (t->flags & PF_KTHREAD)
+ return 0;
+
+ if (state != TASK_INTERRUPTIBLE &&
+ state != TASK_UNINTERRUPTIBLE)
+ return 0;
+
+ return 1;
+}
+
SEC("tp_btf/sched_switch")
int on_switch(u64 *ctx)
{
@@ -92,10 +139,7 @@ int on_switch(u64 *ctx)
ts = bpf_ktime_get_ns();
- if (prev->flags & PF_KTHREAD)
- goto next;
- if (state != TASK_INTERRUPTIBLE &&
- state != TASK_UNINTERRUPTIBLE)
+ if (!can_record(prev, state))
goto next;
stack_id = bpf_get_stackid(ctx, &stacks,
--
2.36.0.rc2.479.g8af0fa9b8e-goog
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