From 27cf5706a04e53f6844c71be1cbbf1df665f5d19 Mon Sep 17 00:00:00 2001 From: Ravi Bangoria Date: Fri, 3 Feb 2017 15:56:42 +0530 Subject: [PATCH] perf sdt: Show proper hint when event not yet in place via 'perf probe' All events from 'perf list', except SDT events, can be directly recorded with 'perf record'. But, the flow is little different for SDT events. Probe points for SDT event needs to be created using 'perf probe' before recording it using 'perf record'. Perf shows misleading hint when a user tries to record SDT event without first creating a probe point. Show proper hint there. Before patch: $ perf record -a -e sdt_glib:idle__add event syntax error: 'sdt_glib:idle__add' \___ unknown tracepoint Error: File /sys/kernel/debug/tracing/events/sdt_glib/idle__add not found. Hint: Perhaps this kernel misses some CONFIG_ setting to enable this feature?. ... After patch: $ perf record -a -e sdt_glib:idle__add event syntax error: 'sdt_glib:idle__add' \___ unknown tracepoint Error: File /sys/kernel/debug/tracing/events/sdt_glib/idle__add not found. Hint: SDT event cannot be directly recorded on. Please first use 'perf probe sdt_glib:idle__add' before recording it. ... $ perf probe sdt_glib:idle__add Added new event: sdt_glib:idle__add (on %idle__add in /usr/lib64/libglib-2.0.so.0.5000.2) You can now use it in all perf tools, such as: perf record -e sdt_glib:idle__add -aR sleep 1 $ perf record -a -e sdt_glib:idle__add [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.175 MB perf.data ] Suggested-and-Acked-by: Ingo Molnar Signed-off-by: Ravi Bangoria Tested-by: Arnaldo Carvalho de Melo Acked-by: Masami Hiramatsu Cc: Alexander Shishkin Cc: Alexis Berlemont Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Naveen N. Rao Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170203102642.17258-1-ravi.bangoria@linux.vnet.ibm.com [ s/Please use/Please first use/ and break the Hint line in two ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/tracing_path.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c index 251b7c342a87..3e606b9c443e 100644 --- a/tools/lib/api/fs/tracing_path.c +++ b/tools/lib/api/fs/tracing_path.c @@ -86,9 +86,13 @@ void put_tracing_file(char *file) free(file); } -static int strerror_open(int err, char *buf, size_t size, const char *filename) +int tracing_path__strerror_open_tp(int err, char *buf, size_t size, + const char *sys, const char *name) { char sbuf[128]; + char filename[PATH_MAX]; + + snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*"); switch (err) { case ENOENT: @@ -99,10 +103,19 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename) * - jirka */ if (debugfs__configured() || tracefs__configured()) { - snprintf(buf, size, - "Error:\tFile %s/%s not found.\n" - "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n", - tracing_events_path, filename); + /* sdt markers */ + if (!strncmp(filename, "sdt_", 4)) { + snprintf(buf, size, + "Error:\tFile %s/%s not found.\n" + "Hint:\tSDT event cannot be directly recorded on.\n" + "\tPlease first use 'perf probe %s:%s' before recording it.\n", + tracing_events_path, filename, sys, name); + } else { + snprintf(buf, size, + "Error:\tFile %s/%s not found.\n" + "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n", + tracing_events_path, filename); + } break; } snprintf(buf, size, "%s", @@ -125,12 +138,3 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename) return 0; } - -int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name) -{ - char path[PATH_MAX]; - - snprintf(path, PATH_MAX, "%s/%s", sys, name ?: "*"); - - return strerror_open(err, buf, size, path); -} -- 2.30.2