Re: [PATCH] perf/x86/intel: Use rdmsrl_safe when initializing RAPL PMU.

Stephane Eranian
2014-04-23T15:14:40Z

On Wed, Apr 23, 2014 at 5:09 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Apr 23, 2014 at 04:49:55PM +0200, Stephane Eranian wrote:
>> On your machine, booted with 3.15-rc2, do you have /sys/devices/power?
>> If not, and you have at least an SNB, you should have RAPL and that
>> RAPL_UNIT MSR.
>>
>> Proof is that if you read that MSR using /dev/cpu/msr it works just fine:
>> # modprobe msr
>> # rdmsr 0x606
>> a1003
>>
>> So something is broken somewhere.
>
> I've not got SNB+ class hardware (for testing). But I believe you that
> there's something funny, I just do not understanding how *msr_safe()
> could cause this.

Or the logic of the test in rapl_cpu_prepare() is wrong, maybe?
Wouldn't rdmsrl_safe() return 0 on success?