Platforms (e.g., VM's) without support for precise mode get a confusing
error message. e.g.,
$ 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.
No hardware sampling interrupt available. No APIC? If so then you can
boot the kernel with the "lapic" boot parameter to force-enable it.
sleep: Terminated
which is not clear that precise mode might be the root problem. With this
patch:
$ perf record -e cycles:p -fo /tmp/perf.data -- sleep 1
Error:
'precise' request not supported. Try removing 'p' modifier
sleep: Terminated
Signed-off-by: David Ahern <dsah...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Robert Richter <robert.rich...@amd.com>
---
tools/perf/builtin-record.c | 5 +++++
tools/perf/builtin-top.c | 4 ++++
2 files changed, 9 insertions(+)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7b8b891..ccf529b 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -294,6 +294,11 @@ try_again:
perf_evsel__name(pos));
rc = -err;
goto out;
+ } else if ((err == ENOTSUP) && (attr->precise_ip)) {
+ ui__error("\'precise\' request not supported. "
+ "Try removing 'p' modifier\n");
+ rc = -err;
+ goto out;
}
printf("\n");
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 0513aaa..0d3653b 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -975,6 +975,10 @@ 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("\'precise\' 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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