If the PEBS is not supported (e.g., a VM) and the precise modifier is
set the user is given a confusing error message:
$ perf top -e cycles:p
The sys_perf_event_open() syscall returned with 95 (Operation not supported).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?
$ perf record -e cycles:p -a -- sleep 1
Error: sys_perf_event_open() syscall returned with 95 (Operation not
supported). /bin/dmesg may provide additional information.
Fatal: No hardware sampling interrupt available. No APIC? If so then you can
boot the kernel with the "lapic" boot parameter to force-enable it.
Which in no way conveys the real error. With this patch:
$ perf top -e cycles:p
PEBS request not supported. Try removing 'p' modifier
$ perf record -e cycles:p -a -- sleep 1
PEBS request not supported. Try removing 'p' modifier
Signed-off-by: David Ahern <dsah...@gmail.com>
Cc: Arnaldo Carvalho de Melo <a...@ghostprotocols.net>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Peter Zijlstra <pet...@infradead.org>
---
tools/perf/builtin-record.c | 4 ++++
tools/perf/builtin-top.c | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f5a6452..911e300 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -267,6 +267,10 @@ try_again:
ui__error("The %s event is not supported.\n",
perf_evsel__name(pos));
exit(EXIT_FAILURE);
+ } else if ((err == ENOTSUP) && (attr->precise_ip)) {
+ ui__error("PEBS request not supported. "
+ "Try removing 'p' modifier\n");
+ exit(EXIT_FAILURE);
}
printf("\n");
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 0ce665c..1706dc9 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -968,6 +968,10 @@ try_again:
ui__error("Too many events are opened.\n"
"Try again after reducing the
number of events\n");
goto out_err;
+ } else if ((err == ENOTSUP) && (attr->precise_ip)) {
+ ui__error("PEBS request not supported. "
+ "Try removing 'p' modifier\n");
+ goto out_err;
}
ui__error("The sys_perf_event_open() syscall "
--
1.7.10.1
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