[tip:perf/core] perf kmem: Show warning when trying to run stat without record

From: tip-bot for Namhyung Kim
Date: Tue May 05 2015 - 23:20:05 EST


Commit-ID: a923e2c4b14f99f70692f82ee7bd63717604b738
Gitweb: http://git.kernel.org/tip/a923e2c4b14f99f70692f82ee7bd63717604b738
Author: Namhyung Kim <namhyung@xxxxxxxxxx>
AuthorDate: Tue, 5 May 2015 23:52:52 +0900
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 5 May 2015 18:13:08 -0300

perf kmem: Show warning when trying to run stat without record

Sometimes one can mistakenly run 'perf kmem stat' without running 'perf
kmem record' before or with a different configuration like recording
--slab and stat --page. Show a warning message like the one below to
inform the user:

# perf kmem stat --page --caller
No page allocation events found. Have you run 'perf kmem record --page'?

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Acked-by: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/1430837572-31395-1-git-send-email-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-kmem.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c
index 828b728..e628bf1 100644
--- a/tools/perf/builtin-kmem.c
+++ b/tools/perf/builtin-kmem.c
@@ -1882,6 +1882,7 @@ int cmd_kmem(int argc, const char **argv, const char *prefix __maybe_unused)
};
struct perf_session *session;
int ret = -1;
+ const char errmsg[] = "No %s allocation events found. Have you run 'perf kmem record --%s'?\n";

perf_config(kmem_config, NULL);
argc = parse_options_subcommand(argc, argv, kmem_options,
@@ -1908,11 +1909,21 @@ int cmd_kmem(int argc, const char **argv, const char *prefix __maybe_unused)
if (session == NULL)
return -1;

+ if (kmem_slab) {
+ if (!perf_evlist__find_tracepoint_by_name(session->evlist,
+ "kmem:kmalloc")) {
+ pr_err(errmsg, "slab", "slab");
+ return -1;
+ }
+ }
+
if (kmem_page) {
- struct perf_evsel *evsel = perf_evlist__first(session->evlist);
+ struct perf_evsel *evsel;

- if (evsel == NULL || evsel->tp_format == NULL) {
- pr_err("invalid event found.. aborting\n");
+ evsel = perf_evlist__find_tracepoint_by_name(session->evlist,
+ "kmem:mm_page_alloc");
+ if (evsel == NULL) {
+ pr_err(errmsg, "page", "page");
return -1;
}

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