Commit 32a951b4 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf evlist: Drop redundant evsel->overwrite indicator 

evsel->overwrite indicator means an event should be put into
overwritable ring buffer. In current implementation, it equals to
evsel->attr.write_backward. To reduce compliexity, remove
evsel->overwrite, use evsel->attr.write_backward instead.

In addition, in __perf_evsel__open(), if kernel doesn't support
write_backward and user explicitly set it in evsel, don't fallback
like other missing feature, since it is meaningless to fall back to
a forward ring buffer in this case: we are unable to stably read
from an forward overwritable ring buffer.

Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1468485287-33422-2-git-send-email-wangnan0@huawei.com


Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent db49120a

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

+1 −0
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ int test__backward_ring_buffer(int subtest __maybe_unused) 
		return TEST_FAIL;

	}



	evlist->backward = true;

	err = perf_evlist__create_maps(evlist, &opts.target);

	if (err < 0) {

		pr_debug("Not enough memory to create thread/cpu maps\n");

tools/perf/util/evlist.c

+2 −2
Original line number Diff line number Diff line
@@ -1003,7 +1003,7 @@ static bool 
perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,

			 struct perf_evsel *evsel)

{

	if (evsel->overwrite)

	if (evsel->attr.write_backward)

		return false;

	return true;

}
@@ -1018,7 +1018,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, 
	evlist__for_each_entry(evlist, evsel) {

		int fd;



		if (evsel->overwrite != (evlist->overwrite && evlist->backward))

		if (!!evsel->attr.write_backward != (evlist->overwrite && evlist->backward))

			continue;



		if (evsel->system_wide && thread)

tools/perf/util/evsel.c

+5 −7
Original line number Diff line number Diff line
@@ -1377,6 +1377,9 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, 
	int pid = -1, err;

	enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;



	if (perf_missing_features.write_backward && evsel->attr.write_backward)

		return -EINVAL;



	if (evsel->system_wide)

		nthreads = 1;

	else
@@ -1407,11 +1410,6 @@ fallback_missing_features: 
	if (perf_missing_features.lbr_flags)

		evsel->attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |

				     PERF_SAMPLE_BRANCH_NO_CYCLES);

	if (perf_missing_features.write_backward) {

		if (evsel->overwrite)

			return -EINVAL;

		evsel->attr.write_backward = false;

	}

retry_sample_id:

	if (perf_missing_features.sample_id_all)

		evsel->attr.sample_id_all = 0;
@@ -1513,7 +1511,7 @@ try_fallback: 
	 */

	if (!perf_missing_features.write_backward && evsel->attr.write_backward) {

		perf_missing_features.write_backward = true;

		goto fallback_missing_features;

		goto out_close;

	} else if (!perf_missing_features.clockid_wrong && evsel->attr.use_clockid) {

		perf_missing_features.clockid_wrong = true;

		goto fallback_missing_features;
@@ -2422,7 +2420,7 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target, 
	"We found oprofile daemon running, please stop it and try again.");

		break;

	case EINVAL:

		if (evsel->overwrite && perf_missing_features.write_backward)

		if (evsel->attr.write_backward && perf_missing_features.write_backward)

			return scnprintf(msg, size, "Reading from overwrite event is not supported by this kernel.");

		if (perf_missing_features.clockid)

			return scnprintf(msg, size, "clockid feature not supported.");

tools/perf/util/evsel.h

+0 −1
Original line number Diff line number Diff line
@@ -114,7 +114,6 @@ struct perf_evsel { 
	bool			tracking;

	bool			per_pkg;

	bool			precise_max;

	bool			overwrite;

	/* parse modifier helper */

	int			exclude_GH;

	int			nr_members;

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