Re: [PATCH] powerpc/perf: fix Threshold Event CounterMultiplier width for P10

[Madhavan Srinivasan <maddy@linux.ibm.com>]

On 10/13/20 9:28 PM, Michal Suchánek wrote:
> On Tue, Oct 13, 2020 at 06:27:05PM +0530, Madhavan Srinivasan wrote:
>> On 10/12/20 4:59 PM, Michal Suchánek wrote:
>>> Hello,
>>>
>>> On Mon, Oct 12, 2020 at 04:01:28PM +0530, Madhavan Srinivasan wrote:
>>>> Power9 and isa v3.1 has 7bit mantissa field for Threshold Event Counter
>>>                     ^^^ Shouldn't his be 3.0?
>> My bad, What I meant was
>>
>> Power9, ISA v3.0 and ISA v3.1 define a 7 bit mantissa field for Threshold
>> Event Counter Multiplier(TECM).
> I am really confused.
>
> The following text and the code suggests that the mantissa is 8bit on
> POWER10 and ISA v3.1.

Ok got it. Will fix the CPU_FTR_ARCH_31 check.

Thanks for review

Maddy
>
> Thanks
>
> Michal
>> Maddy
>>
>>>> Multiplier (TECM). TECM is part of Monitor Mode Control Register A (MMCRA).
>>>> This field along with Threshold Event Counter Exponent (TECE) is used to
>>>> get threshould counter value. In Power10, the width of TECM field is
>>>> increase to 8bits. Patch fixes the current code to modify the MMCRA[TECM]
>>>> extraction macro to handling this changes.
>>>>
>>>> Fixes: 170a315f41c64 ('powerpc/perf: Support to export MMCRA[TEC*] field to userspace')
>>>> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
>>>> ---
>>>>    arch/powerpc/perf/isa207-common.c | 3 +++
>>>>    arch/powerpc/perf/isa207-common.h | 4 ++++
>>>>    2 files changed, 7 insertions(+)
>>>>
>>>> diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c
>>>> index 964437adec18..5fe129f02290 100644
>>>> --- a/arch/powerpc/perf/isa207-common.c
>>>> +++ b/arch/powerpc/perf/isa207-common.c
>>>> @@ -247,6 +247,9 @@ void isa207_get_mem_weight(u64 *weight)
>>>>    	u64 sier = mfspr(SPRN_SIER);
>>>>    	u64 val = (sier & ISA207_SIER_TYPE_MASK) >> ISA207_SIER_TYPE_SHIFT;
>>>> +	if (cpu_has_feature(CPU_FTR_ARCH_31))
>>>> +		mantissa = P10_MMCRA_THR_CTR_MANT(mmcra);
>>>> +
>>>>    	if (val == 0 || val == 7)
>>>>    		*weight = 0;
>>>>    	else
>>>> diff --git a/arch/powerpc/perf/isa207-common.h b/arch/powerpc/perf/isa207-common.h
>>>> index 044de65e96b9..71380e854f48 100644
>>>> --- a/arch/powerpc/perf/isa207-common.h
>>>> +++ b/arch/powerpc/perf/isa207-common.h
>>>> @@ -219,6 +219,10 @@
>>>>    #define MMCRA_THR_CTR_EXP(v)		(((v) >> MMCRA_THR_CTR_EXP_SHIFT) &\
>>>>    						MMCRA_THR_CTR_EXP_MASK)
>>>> +#define P10_MMCRA_THR_CTR_MANT_MASK	0xFFul
>>>> +#define P10_MMCRA_THR_CTR_MANT(v)	(((v) >> MMCRA_THR_CTR_MANT_SHIFT) &\
>>>> +						P10_MMCRA_THR_CTR_MANT_MASK)
>>>> +
>>>>    /* MMCRA Threshold Compare bit constant for power9 */
>>>>    #define p9_MMCRA_THR_CMP_SHIFT	45
>>>> -- 
>>>> 2.26.2
>>>>