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: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 862e69c..6803f5c 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1003,7 +1003,7 @@
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 @@
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)