Re: perf counters: problem with perf record

["Simon Kämpflein" <s.kaempflein@gmx.de>]

Peter Zijlstra schrieb:
> On Sun, 2009-11-15 at 03:14 +1000, Simon Kämpflein wrote:
>> Hello,
>>
>> I have a problem with the new kernel perf tools in kernel 2.6.31.6 (very
>> nice tools by the way). I like to monitor the cache-misses of a program.
>> "perf stat -e cache-misses program" works without problems, but I can't
>> get "perf record -e cache-misses program" working (even running as root
>> and CONFIG_PERF_COUNTERS=y):
>>
>> Error: perfcounter syscall returned with -1 (Operation not supported)
>> Fatal: No CONFIG_PERF_COUNTERS=y kernel support configured?
>>
>> My CPU is a "Intel(R) Pentium(R) M processor 1.80GHz":
> 
> Does the bootlog perchance contain the output of?
> 
>         if (!cpu_has_apic) {
>                 pr_info("no APIC, boot with the \"lapic\" boot parameter
> to force-enable it.\n");
>                 pr_info("no hardware sampling interrupt available.\n");
>                 x86_pmu.apic = 0;
>         }

Yes. I didn't realize that it has something to do with the Performance
Counters because I didn't see that it belongs to the Performance Counter
output.
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.

> And does booting with the suggested lapic parameter cure your problems?
> 

Yes, thank you!

Regars,
Simon