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Commit 626a6b78 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

perf tools: Enable overwrite settings 



This patch allows following config terms and option:

Globally setting events to overwrite;

  # perf record --overwrite ...

Set specific events to be overwrite or no-overwrite.

  # perf record --event cycles/overwrite/ ...
  # perf record --event cycles/no-overwrite/ ...

Add missing config terms and update the config term array size because
the longest string length has changed.

For overwritable events, it automatically selects attr.write_backward
since perf requires it to be backward for reading.

Test result:

  # perf record --overwrite -e syscalls:*enter_nanosleep* usleep 1
  [ perf record: Woken up 2 times to write data ]
  [ perf record: Captured and wrote 0.011 MB perf.data (1 samples) ]
  # perf evlist -v
  syscalls:sys_enter_nanosleep: type: 2, size: 112, config: 0x134, { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|PERIOD|RAW, disabled: 1, inherit: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, write_backward: 1
  # Tip: use 'perf evlist --trace-fields' to show fields for tracepoint events

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1468485287-33422-14-git-send-email-wangnan0@huawei.com


Signed-off-by: default avatarHe Kuang <hekuang@huawei.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent f6cdff83

tools/perf/Documentation/perf-record.txt

+14 −0
Original line number Diff line number Diff line
@@ -367,6 +367,20 @@ options. 
'perf record --dry-run -e' can act as a BPF script compiler if llvm.dump-obj

in config file is set to true.



--overwrite::

Makes all events use an overwritable ring buffer. An overwritable ring

buffer works like a flight recorder: when it gets full, the kernel will

overwrite the oldest records, that thus will never make it to the

perf.data file.



When '--overwrite' and '--switch-output' are used perf records and drops

events until it receives a signal, meaning that something unusual was

detected that warrants taking a snapshot of the most current events,

those fitting in the ring buffer at that moment.



'overwrite' attribute can also be set or canceled for an event using

config terms. For example: 'cycles/overwrite/' and 'instructions/no-overwrite/'.



SEE ALSO

--------

linkperf:perf-stat[1], linkperf:perf-list[1]

tools/perf/builtin-record.c

+1 −0
Original line number Diff line number Diff line
@@ -1399,6 +1399,7 @@ struct option __record_options[] = { 
	OPT_BOOLEAN_SET('i', "no-inherit", &record.opts.no_inherit,

			&record.opts.no_inherit_set,

			"child tasks do not inherit counters"),

	OPT_BOOLEAN(0, "overwrite", &record.opts.overwrite, "use overwrite mode"),

	OPT_UINTEGER('F', "freq", &record.opts.user_freq, "profile at this frequency"),

	OPT_CALLBACK('m', "mmap-pages", &record.opts, "pages[,pages]",

		     "number of mmap data pages and AUX area tracing mmap pages",

tools/perf/perf.h

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ struct record_opts { 
	bool	     record_switch_events;

	bool	     all_kernel;

	bool	     all_user;

	bool	     overwrite;

	unsigned int freq;

	unsigned int mmap_pages;

	unsigned int auxtrace_mmap_pages;

tools/perf/tests/backward-ring-buffer.c

+5 −5
Original line number Diff line number Diff line
@@ -108,7 +108,11 @@ int test__backward_ring_buffer(int subtest __maybe_unused) 
	}



	bzero(&parse_error, sizeof(parse_error));

	err = parse_events(evlist, "syscalls:sys_enter_prctl", &parse_error);

	/*

	 * Set backward bit, ring buffer should be writing from end. Record

	 * it in aux evlist

	 */

	err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error);

	if (err) {

		pr_debug("Failed to parse tracepoint event, try use root\n");

		ret = TEST_SKIP;
@@ -117,10 +121,6 @@ int test__backward_ring_buffer(int subtest __maybe_unused) 


	perf_evlist__config(evlist, &opts, NULL);



	/* Set backward bit, ring buffer should be writing from end */

	evlist__for_each_entry(evlist, evsel)

		evsel->attr.write_backward = 1;



	err = perf_evlist__open(evlist);

	if (err < 0) {

		pr_debug("perf_evlist__open: %s\n",

tools/perf/util/evsel.c

+4 −0
Original line number Diff line number Diff line
@@ -695,6 +695,9 @@ static void apply_config_terms(struct perf_evsel *evsel, 
			 */

			attr->inherit = term->val.inherit ? 1 : 0;

			break;

		case PERF_EVSEL__CONFIG_TERM_OVERWRITE:

			attr->write_backward = term->val.overwrite ? 1 : 0;

			break;

		default:

			break;

		}
@@ -776,6 +779,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts, 


	attr->sample_id_all = perf_missing_features.sample_id_all ? 0 : 1;

	attr->inherit	    = !opts->no_inherit;

	attr->write_backward = opts->overwrite ? 1 : 0;



	perf_evsel__set_sample_bit(evsel, IP);

	perf_evsel__set_sample_bit(evsel, TID);