Messages in this thread Patch in this message | | | Date | Mon, 16 Nov 2009 15:25:53 +1000 | From | Simon Kämpflein <> | Subject | Re: perf counters: problem with perf record |
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Ingo Molnar wrote >> Maybe it's a good idea to add another comment making it clear that the >> performance counters are not fully working in this case. Or detect this >> case in "perf-record" and output a message relating to that. > > Ok. Mind sending a patch that changes the message so that it explains it > all to you more clearly?
Here's a patch for this:
More accurate error message when "perf record" fails because there is no APIC support: --- tools/perf/builtin-record.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 04f335e..77b21f1 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -303,6 +303,10 @@ try_again: printf("\n"); error("perfcounter syscall returned with %d (%s)\n", fd[nr_cpu][counter], strerror(err)); + + if (attr->type == PERF_TYPE_HARDWARE && err == EOPNOTSUPP) + die("No hardware sampling interrupt available. No APIC? Boot the kernel with the \"lapic\" boot parameter to force-enable it.\n"); + die("No CONFIG_PERF_EVENTS=y kernel support configured?\n"); exit(-1); } -- 1.5.4.3
> >>> And does booting with the suggested lapic parameter cure your problems? >>> >> Yes, thank you! > > Great. > > You might want to send another patch that allows the .config enabling of > that lapic boot parameter. It sucks to carry around boot parameters. >
I'm not sure if this is a good idea. Some systems may crash if you force-enable it: http://lkml.indiana.edu/hypermail/linux/kernel/0307.3/1635.html
And I'm also not familiar with the kernel internals on that topic ;)
Simon
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