Parse offcpu-time event using parse_event, in off_cpu_start(), write
evlist fds got from evlist__open() to perf_event_array BPF map.
Signed-off-by: Howard Chu <howardchu95@gmail.com>
---
tools/perf/util/bpf_off_cpu.c | 56 +++++++++++++++-----------
tools/perf/util/bpf_skel/off_cpu.bpf.c | 9 +++++
2 files changed, 41 insertions(+), 24 deletions(-)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index eaef643f50e3..f7233a09ec77 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -13,6 +13,7 @@
#include "util/cgroup.h"
#include "util/strlist.h"
#include <bpf/bpf.h>
+#include <internal/xyarray.h>
#include "bpf_skel/off_cpu.skel.h"
@@ -36,41 +37,27 @@ union off_cpu_data {
u64 array[1024 / sizeof(u64)];
};
+u64 off_cpu_raw_data[1024 / sizeof(u64)];
+
static int off_cpu_config(struct evlist *evlist)
{
- struct evsel *evsel;
- struct perf_event_attr attr = {
- .type = PERF_TYPE_SOFTWARE,
- .config = PERF_COUNT_SW_BPF_OUTPUT,
- .size = sizeof(attr), /* to capture ABI version */
- };
- char *evname = strdup(OFFCPU_EVENT);
-
- if (evname == NULL)
- return -ENOMEM;
+ char off_cpu_event[64];
- evsel = evsel__new(&attr);
- if (!evsel) {
- free(evname);
- return -ENOMEM;
+ scnprintf(off_cpu_event, sizeof(off_cpu_event), "bpf-output/no-inherit=1,name=%s/", OFFCPU_EVENT);
+ if (parse_event(evlist, off_cpu_event)) {
+ pr_err("Failed to open off-cpu event\n");
+ return -1;
}
- evsel->core.attr.freq = 1;
- evsel->core.attr.sample_period = 1;
- /* off-cpu analysis depends on stack trace */
- evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN;
-
- evlist__add(evlist, evsel);
-
- free(evsel->name);
- evsel->name = evname;
-
return 0;
}
static void off_cpu_start(void *arg)
{
struct evlist *evlist = arg;
+ struct evsel *evsel;
+ struct perf_cpu pcpu;
+ int i, err;
/* update task filter for the given workload */
if (skel->rodata->has_task && skel->rodata->uses_tgid &&
@@ -84,6 +71,27 @@ static void off_cpu_start(void *arg)
bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
}
+ /* sample id and fds in BPF's perf_event_array can only be set after record__open() */
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
+ if (evsel == NULL) {
+ pr_err("%s evsel not found\n", OFFCPU_EVENT);
+ return;
+ }
+
+ if (evsel->core.id)
+ skel->bss->sample_id = evsel->core.id[0];
+
+ perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
+ err = bpf_map__update_elem(skel->maps.offcpu_output,
+ &pcpu.cpu, sizeof(__u32),
+ xyarray__entry(evsel->core.fd, pcpu.cpu, 0),
+ sizeof(__u32), BPF_ANY);
+ if (err) {
+ pr_err("Failed to update perf event map for direct off-cpu dumping\n");
+ return;
+ }
+ }
+
skel->bss->enabled = 1;
}
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index 5ea320aa9a53..e2a887228fd9 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -18,6 +18,8 @@
#define MAX_STACKS 32
#define MAX_ENTRIES 102400
+#define MAX_CPUS 4096
+
struct tstamp_data {
__u32 stack_id;
__u32 state;
@@ -39,6 +41,13 @@ struct {
__uint(max_entries, MAX_ENTRIES);
} stacks SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+ __uint(max_entries, MAX_CPUS);
+} offcpu_output SEC(".maps");
+
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
--
2.43.0On Fri, Sep 27, 2024 at 01:27:31PM -0700, Howard Chu wrote:
> Parse offcpu-time event using parse_event, in off_cpu_start(), write
> evlist fds got from evlist__open() to perf_event_array BPF map.
>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> ---
> tools/perf/util/bpf_off_cpu.c | 56 +++++++++++++++-----------
> tools/perf/util/bpf_skel/off_cpu.bpf.c | 9 +++++
> 2 files changed, 41 insertions(+), 24 deletions(-)
>
> diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
> index eaef643f50e3..f7233a09ec77 100644
> --- a/tools/perf/util/bpf_off_cpu.c
> +++ b/tools/perf/util/bpf_off_cpu.c
> @@ -13,6 +13,7 @@
> #include "util/cgroup.h"
> #include "util/strlist.h"
> #include <bpf/bpf.h>
> +#include <internal/xyarray.h>
>
> #include "bpf_skel/off_cpu.skel.h"
>
> @@ -36,41 +37,27 @@ union off_cpu_data {
> u64 array[1024 / sizeof(u64)];
> };
>
> +u64 off_cpu_raw_data[1024 / sizeof(u64)];
> +
> static int off_cpu_config(struct evlist *evlist)
> {
> - struct evsel *evsel;
> - struct perf_event_attr attr = {
> - .type = PERF_TYPE_SOFTWARE,
> - .config = PERF_COUNT_SW_BPF_OUTPUT,
> - .size = sizeof(attr), /* to capture ABI version */
> - };
> - char *evname = strdup(OFFCPU_EVENT);
> -
> - if (evname == NULL)
> - return -ENOMEM;
> + char off_cpu_event[64];
>
> - evsel = evsel__new(&attr);
> - if (!evsel) {
> - free(evname);
> - return -ENOMEM;
> + scnprintf(off_cpu_event, sizeof(off_cpu_event), "bpf-output/no-inherit=1,name=%s/", OFFCPU_EVENT);
Is the 'no-inherit=1' really needed? I guess that's the default and
you won't need it if you open it as a per-cpu event.
> + if (parse_event(evlist, off_cpu_event)) {
> + pr_err("Failed to open off-cpu event\n");
> + return -1;
> }
>
> - evsel->core.attr.freq = 1;
> - evsel->core.attr.sample_period = 1;
> - /* off-cpu analysis depends on stack trace */
> - evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN;
> -
> - evlist__add(evlist, evsel);
> -
> - free(evsel->name);
> - evsel->name = evname;
> -
> return 0;
> }
>
> static void off_cpu_start(void *arg)
> {
> struct evlist *evlist = arg;
> + struct evsel *evsel;
> + struct perf_cpu pcpu;
> + int i, err;
>
> /* update task filter for the given workload */
> if (skel->rodata->has_task && skel->rodata->uses_tgid &&
> @@ -84,6 +71,27 @@ static void off_cpu_start(void *arg)
> bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
> }
>
> + /* sample id and fds in BPF's perf_event_array can only be set after record__open() */
> + evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
> + if (evsel == NULL) {
> + pr_err("%s evsel not found\n", OFFCPU_EVENT);
> + return;
> + }
> +
> + if (evsel->core.id)
> + skel->bss->sample_id = evsel->core.id[0];
Where's it used?
> +
> + perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
> + err = bpf_map__update_elem(skel->maps.offcpu_output,
> + &pcpu.cpu, sizeof(__u32),
I understand you used pcpu.cpu as a key to the offcpu_output map because
it's a basically per-cpu array.
> + xyarray__entry(evsel->core.fd, pcpu.cpu, 0),
But I suspect you should use 'i' instead of pcpu.cpu as an index to the
xyarray.
Thanks,
Namhyung
> + sizeof(__u32), BPF_ANY);
> + if (err) {
> + pr_err("Failed to update perf event map for direct off-cpu dumping\n");
> + return;
> + }
> + }
> +
> skel->bss->enabled = 1;
> }
>
> diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> index 5ea320aa9a53..e2a887228fd9 100644
> --- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
> +++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> @@ -18,6 +18,8 @@
> #define MAX_STACKS 32
> #define MAX_ENTRIES 102400
>
> +#define MAX_CPUS 4096
> +
> struct tstamp_data {
> __u32 stack_id;
> __u32 state;
> @@ -39,6 +41,13 @@ struct {
> __uint(max_entries, MAX_ENTRIES);
> } stacks SEC(".maps");
>
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(key_size, sizeof(__u32));
> + __uint(value_size, sizeof(__u32));
> + __uint(max_entries, MAX_CPUS);
> +} offcpu_output SEC(".maps");
> +
> struct {
> __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
> __uint(map_flags, BPF_F_NO_PREALLOC);
> --
> 2.43.0
>
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