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Subject[PATCH 5/5] perf ftrace: Implement cpu and task filters in BPF
Date
Honor cpu and task options to set up filters (by pid or tid) in the
BPF program. For example, the following command will show latency of
the mutex_lock for process 2570.

# perf ftrace latency -b -T mutex_lock -p 2570 sleep 3
# DURATION | COUNT | GRAPH |
0 - 1 us | 675 | ############################## |
1 - 2 us | 9 | |
2 - 4 us | 0 | |
4 - 8 us | 0 | |
8 - 16 us | 0 | |
16 - 32 us | 0 | |
32 - 64 us | 0 | |
64 - 128 us | 0 | |
128 - 256 us | 0 | |
256 - 512 us | 0 | |
512 - 1024 us | 0 | |
1 - 2 ms | 0 | |
2 - 4 ms | 0 | |
4 - 8 ms | 0 | |
8 - 16 ms | 0 | |
16 - 32 ms | 0 | |
32 - 64 ms | 0 | |
64 - 128 ms | 0 | |
128 - 256 ms | 0 | |
256 - 512 ms | 0 | |
512 - 1024 ms | 0 | |
1 - ... s | 0 | |

Committer testing:

Looking at faults on a firefox process:

# strace -e bpf perf ftrace latency -b -p 1674378 -T __handle_mm_fault
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=2, insns=0x7ffee1fee740, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0, func_info_rec_size=0, func_info=NULL, func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0, attach_btf_id=0, attach_prog_fd=0}, 128) = 3
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\0\20\0\0\0\20\0\0\0\5\0\0\0\1\0\0\0\0\0\0\1"..., btf_log_buf=NULL, btf_size=45, btf_log_size=0, btf_log_level=0}, 128) = 3
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\0000\0\0\0000\0\0\0\t\0\0\0\1\0\0\0\0\0\0\1"..., btf_log_buf=NULL, btf_size=81, btf_log_size=0, btf_log_level=0}, 128) = 3
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\08\0\0\08\0\0\0\t\0\0\0\0\0\0\0\0\0\0\1"..., btf_log_buf=NULL, btf_size=89, btf_log_size=0, btf_log_level=0}, 128) = 3
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\0\f\0\0\0\f\0\0\0\7\0\0\0\1\0\0\0\0\0\0\20"..., btf_log_buf=NULL, btf_size=43, btf_log_size=0, btf_log_level=0}, 128) = 3
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\0000\0\0\0000\0\0\0\t\0\0\0\1\0\0\0\0\0\0\1"..., btf_log_buf=NULL, btf_size=81, btf_log_size=0, btf_log_level=0}, 128) = 3
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\0000\0\0\0000\0\0\0\5\0\0\0\0\0\0\0\0\0\0\1"..., btf_log_buf=NULL, btf_size=77, btf_log_size=0, btf_log_level=0}, 128) = -1 EINVAL (Invalid argument)
bpf(BPF_BTF_LOAD, {btf="\237\353\1\0\30\0\0\0\0\0\0\0 \3\0\0 \3\0\0\306\3\0\0\0\0\0\0\0\0\0\2"..., btf_log_buf=NULL, btf_size=1790, btf_log_size=0, btf_log_level=0}, 128) = 3
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=32, max_entries=1, map_flags=0, inner_map_fd=0, map_name="", map_ifindex=0, btf_fd=0, btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0}, 128) = 4
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=5, insns=0x7ffee1fee570, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0, func_info_rec_size=0, func_info=NULL, func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0, attach_btf_id=0, attach_prog_fd=0}, 128) = 5
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=4, max_entries=1, map_flags=BPF_F_MMAPABLE, inner_map_fd=0, map_name="", map_ifindex=0, btf_fd=0, btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0}, 128) = 4
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=2, insns=0x7ffee1fee3c0, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="test", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0, func_info_rec_size=0, func_info=NULL, func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0, attach_btf_id=0, attach_prog_fd=0}, 128) = 4
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_HASH, key_size=8, value_size=8, max_entries=10000, map_flags=0, inner_map_fd=0, map_name="functime", map_ifindex=0, btf_fd=3, btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0}, 128) = 4
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_HASH, key_size=4, value_size=1, max_entries=1, map_flags=0, inner_map_fd=0, map_name="cpu_filter", map_ifindex=0, btf_fd=3, btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0}, 128) = 5
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_HASH, key_size=4, value_size=1, max_entries=36, map_flags=0, inner_map_fd=0, map_name="task_filter", map_ifindex=0, btf_fd=3, btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0}, 128) = 6
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_PERCPU_ARRAY, key_size=4, value_size=8, max_entries=22, map_flags=0, inner_map_fd=0, map_name="latency", map_ifindex=0, btf_fd=3, btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0}, 128) = 7
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=12, max_entries=1, map_flags=BPF_F_MMAPABLE, inner_map_fd=0, map_name="func_lat.bss", map_ifindex=0, btf_fd=3, btf_key_type_id=0, btf_value_type_id=32, btf_vmlinux_value_type_id=0}, 128) = 8
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=8, key=0x7ffee1fee580, value=0x7f01d940a000, flags=BPF_ANY}, 128) = 0
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_KPROBE, insn_cnt=42, insns=0x1871f30, license="", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(5, 14, 16), prog_flags=0, prog_name="func_begin", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=3, func_info_rec_size=8, func_info=0x18746a0, func_info_cnt=1, line_info_rec_size=16, line_info=0x1874550, line_info_cnt=20, attach_btf_id=0, attach_prog_fd=0}, 128) = 9
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_KPROBE, insn_cnt=99, insns=0x18769b0, license="", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(5, 14, 16), prog_flags=0, prog_name="func_end", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=3, func_info_rec_size=8, func_info=0x188a640, func_info_cnt=1, line_info_rec_size=16, line_info=0x188a660, line_info_cnt=20, attach_btf_id=0, attach_prog_fd=0}, 128) = 10
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=6, key=0x7ffee1fee8e0, value=0x7ffee1fee8df, flags=BPF_ANY}, 128) = 0
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_TRACEPOINT, insn_cnt=2, insns=0x7ffee1fee3c0, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0, func_info_rec_size=0, func_info=NULL, func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0, attach_btf_id=0, attach_prog_fd=0}, 128) = 12
bpf(BPF_LINK_CREATE, {link_create={prog_fd=12, target_fd=-1, attach_type=0x29 /* BPF_??? */, flags=0}}, 128) = -1 EINVAL (Invalid argument)
^Cstrace: Process 1702285 detached
# DURATION | COUNT | GRAPH |
0 - 1 us | 109 | ################# |
1 - 2 us | 127 | ################### |
2 - 4 us | 36 | ##### |
4 - 8 us | 20 | ### |
8 - 16 us | 2 | |
16 - 32 us | 0 | |
32 - 64 us | 0 | |
64 - 128 us | 0 | |
128 - 256 us | 0 | |
256 - 512 us | 0 | |
512 - 1024 us | 0 | |
1 - 2 ms | 0 | |
2 - 4 ms | 0 | |
4 - 8 ms | 0 | |
8 - 16 ms | 0 | |
16 - 32 ms | 0 | |
32 - 64 ms | 0 | |
64 - 128 ms | 0 | |
128 - 256 ms | 0 | |
256 - 512 ms | 0 | |
512 - 1024 ms | 0 | |
1 - ... s | 0 | |

#

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Changbin Du <changbin.du@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20211129231830.1117781-6-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf_ftrace.c | 42 ++++++++++++++++++++-
tools/perf/util/bpf_skel/func_latency.bpf.c | 21 +++++++++++
2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf_ftrace.c b/tools/perf/util/bpf_ftrace.c
index ec4e2f5a2fc4..f00a2de6778c 100644
--- a/tools/perf/util/bpf_ftrace.c
+++ b/tools/perf/util/bpf_ftrace.c
@@ -7,7 +7,9 @@

#include "util/ftrace.h"
#include "util/cpumap.h"
+#include "util/thread_map.h"
#include "util/debug.h"
+#include "util/evlist.h"
#include "util/bpf_counter.h"

#include "util/bpf_skel/func_latency.skel.h"
@@ -16,7 +18,8 @@ static struct func_latency_bpf *skel;

int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace)
{
- int err;
+ int fd, err;
+ int i, ncpus = 1, ntasks = 1;
struct filter_entry *func;

if (!list_is_singular(&ftrace->filters)) {
@@ -33,6 +36,17 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace)
return -1;
}

+ /* don't need to set cpu filter for system-wide mode */
+ if (ftrace->target.cpu_list) {
+ ncpus = perf_cpu_map__nr(ftrace->evlist->core.cpus);
+ bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
+ }
+
+ if (target__has_task(&ftrace->target) || target__none(&ftrace->target)) {
+ ntasks = perf_thread_map__nr(ftrace->evlist->core.threads);
+ bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+ }
+
set_max_rlimit();

err = func_latency_bpf__load(skel);
@@ -41,6 +55,32 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace)
goto out;
}

+ if (ftrace->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 = cpu_map__cpu(ftrace->evlist->core.cpus, i);
+ bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
+ }
+ }
+
+ if (target__has_task(&ftrace->target) || target__none(&ftrace->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(ftrace->evlist->core.threads, i);
+ bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
+ }
+ }
+
skel->links.func_begin = bpf_program__attach_kprobe(skel->progs.func_begin,
false, func->name);
if (IS_ERR(skel->links.func_begin)) {
diff --git a/tools/perf/util/bpf_skel/func_latency.bpf.c b/tools/perf/util/bpf_skel/func_latency.bpf.c
index ccd96b09fc42..ea94187fe443 100644
--- a/tools/perf/util/bpf_skel/func_latency.bpf.c
+++ b/tools/perf/util/bpf_skel/func_latency.bpf.c
@@ -37,6 +37,8 @@ struct {


int enabled = 0;
+int has_cpu = 0;
+int has_task = 0;

SEC("kprobe/func")
int BPF_PROG(func_begin)
@@ -47,6 +49,25 @@ int BPF_PROG(func_begin)
return 0;

key = bpf_get_current_pid_tgid();
+
+ 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) {
+ __u32 pid = key & 0xffffffff;
+ __u8 *ok;
+
+ ok = bpf_map_lookup_elem(&task_filter, &pid);
+ if (!ok)
+ return 0;
+ }
+
now = bpf_ktime_get_ns();

// overwrite timestamp for nested functions
--
2.34.1.173.g76aa8bc2d0-goog
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