perf ftrace: Add -b/--use-bpf option for latency subcommand

The -b/--use-bpf option is to use BPF to get latency info of kernel
functions.  It'd have better performance impact and I observed that
latency of same function is smaller than before when using BPF.

Committer testing:

  # strace -e bpf perf ftrace latency -b -T __handle_mm_fault -a sleep 1
  bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=2, insns=0x7fff51914e00, 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\350\2\0\0\350\2\0\0\353\2\0\0\0\0\0\0\0\0\0\2"..., btf_log_buf=NULL, btf_size=1515, 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=0x7fff51914c30, 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=0x7fff51914a80, 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=1, 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) = 7
  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) = 8
  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="func_lat.bss", map_ifindex=0, btf_fd=3, btf_key_type_id=0, btf_value_type_id=30, btf_vmlinux_value_type_id=0}, 128) = 9
  bpf(BPF_MAP_UPDATE_ELEM, {map_fd=9, key=0x7fff51914c40, value=0x7f6e99be2000, flags=BPF_ANY}, 128) = 0
  bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_KPROBE, insn_cnt=18, insns=0x11e4160, 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=0x11dfc50, func_info_cnt=1, line_info_rec_size=16, line_info=0x11e04c0, line_info_cnt=9, attach_btf_id=0, attach_prog_fd=0}, 128) = 10
  bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_KPROBE, insn_cnt=99, insns=0x11ded70, 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=0x11dfc70, func_info_cnt=1, line_info_rec_size=16, line_info=0x11f6e10, line_info_cnt=20, attach_btf_id=0, attach_prog_fd=0}, 128) = 11
  bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_TRACEPOINT, insn_cnt=2, insns=0x7fff51914a80, 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) = 13
  bpf(BPF_LINK_CREATE, {link_create={prog_fd=13, target_fd=-1, attach_type=0x29 /* BPF_??? */, flags=0}}, 128) = -1 EINVAL (Invalid argument)
  --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=1699992, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  bpf(BPF_MAP_LOOKUP_ELEM, {map_fd=8, key=0x7fff51914f84, value=0x11f6fa0, flags=BPF_ANY}, 128) = 0
  #   DURATION     |      COUNT | GRAPH                                          |
       0 - 1    us |         52 | ###################                            |
       1 - 2    us |         36 | #############                                  |
       2 - 4    us |         24 | #########                                      |
       4 - 8    us |          7 | ##                                             |
       8 - 16   us |          1 |                                                |
      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 |                                                |
  +++ exited with 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: Athira Jajeev <atrajeev@linux.vnet.ibm.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/20211215185154.360314-5-namhyung@kernel.org
[ Add missing util/cpumap.h include and removed unused 'fd' variable ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 92 insertions, 66 deletions

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 8fd3c9c44c69..2b54e2ddc80a 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -30,36 +30,12 @@
 #include "strfilter.h"
 #include "util/cap.h"
 #include "util/config.h"
+#include "util/ftrace.h"
 #include "util/units.h"
 #include "util/parse-sublevel-options.h"
 
 #define DEFAULT_TRACER  "function_graph"
 
-struct perf_ftrace {
-	struct evlist		*evlist;
-	struct target		target;
-	const char		*tracer;
-	struct list_head	filters;
-	struct list_head	notrace;
-	struct list_head	graph_funcs;
-	struct list_head	nograph_funcs;
-	int			graph_depth;
-	unsigned long		percpu_buffer_size;
-	bool			inherit;
-	int			func_stack_trace;
-	int			func_irq_info;
-	int			graph_nosleep_time;
-	int			graph_noirqs;
-	int			graph_verbose;
-	int			graph_thresh;
-	unsigned int		initial_delay;
-};
-
-struct filter_entry {
-	struct list_head	list;
-	char			name[];
-};
-
 static volatile int workload_exec_errno;
 static bool done;
 
@@ -704,8 +680,6 @@ out:
 	return (done && !workload_exec_errno) ? 0 : -1;
 }
 
-#define NUM_BUCKET  22  /* 20 + 2 (for outliers in both direction) */
-
 static void make_histogram(int buckets[], char *buf, size_t len, char *linebuf)
 {
 	char *p, *q;
@@ -816,69 +790,116 @@ static void display_histogram(int buckets[])
 
 }
 
-static int __cmd_latency(struct perf_ftrace *ftrace)
+static int prepare_func_latency(struct perf_ftrace *ftrace)
 {
 	char *trace_file;
-	int trace_fd;
-	char buf[4096];
-	char line[256];
-	struct pollfd pollfd = {
-		.events = POLLIN,
-	};
-	int buckets[NUM_BUCKET] = { };
+	int fd;
 
-	if (!(perf_cap__capable(CAP_PERFMON) ||
-	      perf_cap__capable(CAP_SYS_ADMIN))) {
-		pr_err("ftrace only works for %s!\n",
-#ifdef HAVE_LIBCAP_SUPPORT
-		"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
-#else
-		"root"
-#endif
-		);
-		return -1;
-	}
+	if (ftrace->target.use_bpf)
+		return perf_ftrace__latency_prepare_bpf(ftrace);
 
 	if (reset_tracing_files(ftrace) < 0) {
 		pr_err("failed to reset ftrace\n");
-		goto out;
+		return -1;
 	}
 
 	/* reset ftrace buffer */
 	if (write_tracing_file("trace", "0") < 0)
-		goto out;
+		return -1;
 
 	if (set_tracing_options(ftrace) < 0)
-		goto out_reset;
+		return -1;
 
 	/* force to use the function_graph tracer to track duration */
 	if (write_tracing_file("current_tracer", "function_graph") < 0) {
 		pr_err("failed to set current_tracer to function_graph\n");
-		goto out_reset;
+		return -1;
 	}
 
 	trace_file = get_tracing_file("trace_pipe");
 	if (!trace_file) {
 		pr_err("failed to open trace_pipe\n");
-		goto out_reset;
+		return -1;
 	}
 
-	trace_fd = open(trace_file, O_RDONLY);
+	fd = open(trace_file, O_RDONLY);
+	if (fd < 0)
+		pr_err("failed to open trace_pipe\n");
 
 	put_tracing_file(trace_file);
+	return fd;
+}
 
-	if (trace_fd < 0) {
-		pr_err("failed to open trace_pipe\n");
-		goto out_reset;
+static int start_func_latency(struct perf_ftrace *ftrace)
+{
+	if (ftrace->target.use_bpf)
+		return perf_ftrace__latency_start_bpf(ftrace);
+
+	if (write_tracing_file("tracing_on", "1") < 0) {
+		pr_err("can't enable tracing\n");
+		return -1;
 	}
 
+	return 0;
+}
+
+static int stop_func_latency(struct perf_ftrace *ftrace)
+{
+	if (ftrace->target.use_bpf)
+		return perf_ftrace__latency_stop_bpf(ftrace);
+
+	write_tracing_file("tracing_on", "0");
+	return 0;
+}
+
+static int read_func_latency(struct perf_ftrace *ftrace, int buckets[])
+{
+	if (ftrace->target.use_bpf)
+		return perf_ftrace__latency_read_bpf(ftrace, buckets);
+
+	return 0;
+}
+
+static int cleanup_func_latency(struct perf_ftrace *ftrace)
+{
+	if (ftrace->target.use_bpf)
+		return perf_ftrace__latency_cleanup_bpf(ftrace);
+
+	reset_tracing_files(ftrace);
+	return 0;
+}
+
+static int __cmd_latency(struct perf_ftrace *ftrace)
+{
+	int trace_fd;
+	char buf[4096];
+	char line[256];
+	struct pollfd pollfd = {
+		.events = POLLIN,
+	};
+	int buckets[NUM_BUCKET] = { };
+
+	if (!(perf_cap__capable(CAP_PERFMON) ||
+	      perf_cap__capable(CAP_SYS_ADMIN))) {
+		pr_err("ftrace only works for %s!\n",
+#ifdef HAVE_LIBCAP_SUPPORT
+		"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
+#else
+		"root"
+#endif
+		);
+		return -1;
+	}
+
+	trace_fd = prepare_func_latency(ftrace);
+	if (trace_fd < 0)
+		goto out;
+
 	fcntl(trace_fd, F_SETFL, O_NONBLOCK);
 	pollfd.fd = trace_fd;
 
-	if (write_tracing_file("tracing_on", "1") < 0) {
-		pr_err("can't enable tracing\n");
-		goto out_close_fd;
-	}
+	if (start_func_latency(ftrace) < 0)
+		goto out;
 
 	evlist__start_workload(ftrace->evlist);
 
@@ -896,29 +917,30 @@ static int __cmd_latency(struct perf_ftrace *ftrace)
 		}
 	}
 
-	write_tracing_file("tracing_on", "0");
+	stop_func_latency(ftrace);
 
 	if (workload_exec_errno) {
 		const char *emsg = str_error_r(workload_exec_errno, buf, sizeof(buf));
 		pr_err("workload failed: %s\n", emsg);
-		goto out_close_fd;
+		goto out;
 	}
 
 	/* read remaining buffer contents */
-	while (true) {
+	while (!ftrace->target.use_bpf) {
 		int n = read(trace_fd, buf, sizeof(buf) - 1);
 		if (n <= 0)
 			break;
 		make_histogram(buckets, buf, n, line);
 	}
 
+	read_func_latency(ftrace, buckets);
+
 	display_histogram(buckets);
 
-out_close_fd:
-	close(trace_fd);
-out_reset:
-	reset_tracing_files(ftrace);
 out:
+	close(trace_fd);
+	cleanup_func_latency(ftrace);
+
 	return (done && !workload_exec_errno) ? 0 : -1;
 }
 
@@ -1144,6 +1166,10 @@ int cmd_ftrace(int argc, const char **argv)
 	const struct option latency_options[] = {
 	OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",
 		     "Show latency of given function", parse_filter_func),
+#ifdef HAVE_BPF_SKEL
+	OPT_BOOLEAN('b', "use-bpf", &ftrace.target.use_bpf,
+		    "Use BPF to measure function latency"),
+#endif
 	OPT_PARENT(common_options),
 	};
 	const struct option *options = ftrace_options;