Set the perf_event map in BPF for dumping off-cpu samples.
Set the offcpu_thresh to specify the threshold.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-5-howardchu95@gmail.com
[ Added some missing iteration variables to off_cpu_config() and fixed up
a manually edited patch hunk line boundary line ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf_off_cpu.c | 25 +++++++++++++++++++++++++
tools/perf/util/bpf_skel/off_cpu.bpf.c | 11 +++++++++++
2 files changed, 36 insertions(+)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 558c5e5c2dc3..61729a65b529 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"
@@ -60,6 +61,9 @@ static int off_cpu_config(struct evlist *evlist)
static void off_cpu_start(void *arg)
{
struct evlist *evlist = arg;
+ struct evsel *evsel;
+ struct perf_cpu pcpu;
+ int i;
/* update task filter for the given workload */
if (skel->rodata->has_task && skel->rodata->uses_tgid &&
@@ -73,6 +77,25 @@ static void off_cpu_start(void *arg)
bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
}
+ /* update BPF perf_event map */
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
+ if (evsel == NULL) {
+ pr_err("%s evsel not found\n", OFFCPU_EVENT);
+ return;
+ }
+
+ perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
+ int err;
+
+ err = bpf_map__update_elem(skel->maps.offcpu_output, &pcpu.cpu, sizeof(__u32),
+ xyarray__entry(evsel->core.fd, i, 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;
}
@@ -261,6 +284,8 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
}
+ skel->bss->offcpu_thresh_ns = opts->off_cpu_thresh_us * 1000;
+
err = off_cpu_bpf__attach(skel);
if (err) {
pr_err("Failed to attach off-cpu BPF skeleton\n");
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index c152116df72f..c87132e01eb3 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);
@@ -97,6 +106,8 @@ const volatile bool uses_cgroup_v1 = false;
int perf_subsys_id = -1;
+__u64 offcpu_thresh_ns;
+
/*
* Old kernel used to call it task_struct->state and now it's '__state'.
* Use BPF CO-RE "ignored suffix rule" to deal with it like below:
--
2.43.0On Tue, Nov 12, 2024 at 4:28 PM Howard Chu <howardchu95@gmail.com> wrote:
>
> Set the perf_event map in BPF for dumping off-cpu samples.
>
> Set the offcpu_thresh to specify the threshold.
>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: James Clark <james.clark@linaro.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Link: https://lore.kernel.org/r/20241108204137.2444151-5-howardchu95@gmail.com
> [ Added some missing iteration variables to off_cpu_config() and fixed up
> a manually edited patch hunk line boundary line ]
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/perf/util/bpf_off_cpu.c | 25 +++++++++++++++++++++++++
> tools/perf/util/bpf_skel/off_cpu.bpf.c | 11 +++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
> index 558c5e5c2dc3..61729a65b529 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"
>
> @@ -60,6 +61,9 @@ static int off_cpu_config(struct evlist *evlist)
> static void off_cpu_start(void *arg)
> {
> struct evlist *evlist = arg;
> + struct evsel *evsel;
> + struct perf_cpu pcpu;
> + int i;
>
> /* update task filter for the given workload */
> if (skel->rodata->has_task && skel->rodata->uses_tgid &&
> @@ -73,6 +77,25 @@ static void off_cpu_start(void *arg)
> bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
> }
>
> + /* update BPF perf_event map */
> + evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
> + if (evsel == NULL) {
> + pr_err("%s evsel not found\n", OFFCPU_EVENT);
> + return;
> + }
> +
> + perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
> + int err;
> +
> + err = bpf_map__update_elem(skel->maps.offcpu_output, &pcpu.cpu, sizeof(__u32),
> + xyarray__entry(evsel->core.fd, i, 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;
> }
>
> @@ -261,6 +284,8 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
> }
> }
>
> + skel->bss->offcpu_thresh_ns = opts->off_cpu_thresh_us * 1000;
Thanks for the suffixes, readability++.
Ian
> +
> err = off_cpu_bpf__attach(skel);
> if (err) {
> pr_err("Failed to attach off-cpu BPF skeleton\n");
> diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> index c152116df72f..c87132e01eb3 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);
> @@ -97,6 +106,8 @@ const volatile bool uses_cgroup_v1 = false;
>
> int perf_subsys_id = -1;
>
> +__u64 offcpu_thresh_ns;
> +
> /*
> * Old kernel used to call it task_struct->state and now it's '__state'.
> * Use BPF CO-RE "ignored suffix rule" to deal with it like below:
> --
> 2.43.0
>
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