From 2305c82fb35dd2c8c9533303bb1693f1636c66e4 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Thu, 13 Sep 2012 14:59:15 -0600 Subject: perf tools: Give user better message if precise is not supported 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 may not be supported. Try removing 'p' modifier sleep: Terminated v2: softened message to 'may not be' supported per Robert's suggestion Signed-off-by: David Ahern Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Robert Richter Link: http://lkml.kernel.org/r/1347569955-54626-4-git-send-email-dsahern@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-top.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/perf/builtin-top.c') diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index fb9da71eba1f..f2ecd498c72d 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -977,6 +977,10 @@ 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 == EOPNOTSUPP) && (attr->precise_ip)) { + ui__error("\'precise\' request may not be supported. " + "Try removing 'p' modifier\n"); + goto out_err; } ui__error("The sys_perf_event_open() syscall " -- cgit v1.2.3