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Commit ff7a4f98 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf trace: Allow dumping a BPF map after setting up BPF events 

Initial use case:

Dumping the maps setup by tools/perf/examples/bpf/augmented_raw_syscalls.c,
which so far are just booleans, showing just non-zeroed entries:

  # cat ~/.perfconfig
  [llvm]
	dump-obj = true
	clang-opt = -g
  [trace]
	#add_events = /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.o
	add_events = /wb/augmented_raw_syscalls.o
  $ date
  Tue Feb 19 16:29:33 -03 2019
  $ ls -la /wb/augmented_raw_syscalls.o
  -rwxr-xr-x. 1 root root 14048 Jan 24 12:09 /wb/augmented_raw_syscalls.o
  $ file /wb/augmented_raw_syscalls.o
  /wb/augmented_raw_syscalls.o: ELF 64-bit LSB relocatable, eBPF, version 1 (SYSV), with debug_info, not stripped
  $
  # trace -e recvmmsg,sendmmsg --map-dump foobar
  ERROR: BPF map "foobar" not found
  # trace -e recvmmsg,sendmmsg --map-dump filtered_pids
  ERROR: BPF map "filtered_pids" not found
  # trace -e recvmmsg,sendmmsg --map-dump pids_filtered
  [2583] = 1,
  [2267] = 1,
  ^Z
  [1]+  Stopped                 trace -e recvmmsg,sendmmsg --map-dump pids_filtered
  # pidof trace
  2267
  # ps ax|grep gnome-terminal|grep -v grep
  2583 ?        Ssl   58:33 /usr/libexec/gnome-terminal-server
  ^C
  # trace -e recvmmsg,sendmmsg --map-dump syscalls
  [299] = 1,
  [307] = 1,
  ^C
  # grep x64_recvmmsg arch/x86/entry/syscalls/syscall_64.tbl
  299	64	recvmmsg		__x64_sys_recvmmsg
  # grep x64_sendmmsg arch/x86/entry/syscalls/syscall_64.tbl
  307	64	sendmmsg		__x64_sys_sendmmsg
  #

Next step probably will be something like 'perf stat's --interval-print and
--interval-clear.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lkml.kernel.org/n/tip-ztxj25rtx37ixo9cfajt8ocy@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent d19f8564

tools/perf/Documentation/perf-trace.txt

+8 −0
Original line number Diff line number Diff line
@@ -210,6 +210,14 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs. 
	may happen, for instance, when a thread gets migrated to a different CPU

	while processing a syscall.



--map-dump::

	Dump BPF maps setup by events passed via -e, for instance the augmented_raw_syscalls

	living in tools/perf/examples/bpf/augmented_raw_syscalls.c. For now this

	dumps just boolean map values and integer keys, in time this will print in hex

	by default and use BTF when available, as well as use functions to do pretty

	printing using the existing 'perf trace' syscall arg beautifiers to map integer

	arguments to strings (pid to comm, syscall id to syscall name, etc).





PAGEFAULTS

----------

tools/perf/builtin-trace.c

+19 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <traceevent/event-parse.h>

#include <api/fs/tracing_path.h>

#include <bpf/bpf.h>

#include "util/bpf_map.h"

#include "builtin.h"

#include "util/cgroup.h"

#include "util/color.h"
@@ -87,6 +88,9 @@ struct trace { 
					  *augmented;

		}		events;

	} syscalls;

	struct {

		struct bpf_map *map;

	} dump;

	struct record_opts	opts;

	struct perf_evlist	*evlist;

	struct machine		*host;
@@ -2997,6 +3001,9 @@ static int trace__run(struct trace *trace, int argc, const char **argv) 
	if (err < 0)

		goto out_error_apply_filters;



	if (trace->dump.map)

		bpf_map__fprintf(trace->dump.map, trace->output);



	err = perf_evlist__mmap(evlist, trace->opts.mmap_pages);

	if (err < 0)

		goto out_error_mmap;
@@ -3686,6 +3693,7 @@ int cmd_trace(int argc, const char **argv) 
		.max_stack = UINT_MAX,

		.max_events = ULONG_MAX,

	};

	const char *map_dump_str = NULL;

	const char *output_name = NULL;

	const struct option trace_options[] = {

	OPT_CALLBACK('e', "event", &trace, "event",
@@ -3718,6 +3726,9 @@ int cmd_trace(int argc, const char **argv) 
	OPT_CALLBACK(0, "duration", &trace, "float",

		     "show only events with duration > N.M ms",

		     trace__set_duration),

#ifdef HAVE_LIBBPF_SUPPORT

	OPT_STRING(0, "map-dump", &map_dump_str, "BPF map", "BPF map to periodically dump"),

#endif

	OPT_BOOLEAN(0, "sched", &trace.sched, "show blocking scheduler events"),

	OPT_INCR('v', "verbose", &verbose, "be more verbose"),

	OPT_BOOLEAN('T', "time", &trace.full_time,
@@ -3812,6 +3823,14 @@ int cmd_trace(int argc, const char **argv) 


	err = -1;



	if (map_dump_str) {

		trace.dump.map = bpf__find_map_by_name(map_dump_str);

		if (trace.dump.map == NULL) {

			pr_err("ERROR: BPF map \"%s\" not found\n", map_dump_str);

			goto out;

		}

	}



	if (trace.trace_pgfaults) {

		trace.opts.sample_address = true;

		trace.opts.sample_time = true;