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Commit 204721d7 authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
Browse files

perf top: Add overwrite fall back 



Switch to non-overwrite mode if kernel doesnot support overwrite
ringbuffer.

It's only effect when overwrite mode is supported.  No change to current
behavior.

Signed-off-by: default avatarKan Liang <kan.liang@intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-14-git-send-email-kan.liang@intel.com


[ Use perf_missing_features.write_backward instead of the non merged is_write_backward_fail() ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9a831b3a

tools/perf/builtin-top.c

+36 −0
Original line number Diff line number Diff line
@@ -943,6 +943,27 @@ static int perf_top__overwrite_check(struct perf_top *top) 
	return 0;

}



static int perf_top_overwrite_fallback(struct perf_top *top,

				       struct perf_evsel *evsel)

{

	struct record_opts *opts = &top->record_opts;

	struct perf_evlist *evlist = top->evlist;

	struct perf_evsel *counter;



	if (!opts->overwrite)

		return 0;



	/* only fall back when first event fails */

	if (evsel != perf_evlist__first(evlist))

		return 0;



	evlist__for_each_entry(evlist, counter)

		counter->attr.write_backward = false;

	opts->overwrite = false;

	ui__warning("fall back to non-overwrite mode\n");

	return 1;

}



static int perf_top__start_counters(struct perf_top *top)

{

	char msg[BUFSIZ];
@@ -967,6 +988,21 @@ static int perf_top__start_counters(struct perf_top *top) 
try_again:

		if (perf_evsel__open(counter, top->evlist->cpus,

				     top->evlist->threads) < 0) {



			/*

			 * Specially handle overwrite fall back.

			 * Because perf top is the only tool which has

			 * overwrite mode by default, support

			 * both overwrite and non-overwrite mode, and

			 * require consistent mode for all events.

			 *

			 * May move it to generic code with more tools

			 * have similar attribute.

			 */

			if (perf_missing_features.write_backward &&

			    perf_top_overwrite_fallback(top, counter))

				goto try_again;



			if (perf_evsel__fallback(counter, errno, msg, sizeof(msg))) {

				if (verbose > 0)

					ui__warning("%s\n", msg);