linux-kernel - Re: [PATCH] perf/x86: fix Haswell precise store data source encoding

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Date:	Thu, 15 May 2014 16:43:01 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Jiri Olsa <jolsa@...hat.com>, Joe Mario <jmario@...hat.com>,
	Don Zickus <dzickus@...hat.com>
Subject: Re: [PATCH] perf/x86: fix Haswell precise store data source encoding

On Thu, May 15, 2014 at 4:32 PM, Andi Kleen <ak@...ux.intel.com> wrote:
> On Thu, May 15, 2014 at 01:53:37PM +0200, Stephane Eranian wrote:
>>
>> This patches fixes a bug in  precise_store_data_hsw() whereby
>> it would set the data source memory level to the wrong value.
>>
>> As per the the SDM Vol 3b Table 18-41 (Layout of Data Linear
>> Address Information in PEBS Record), when status bit 0 is set
>> this is a L1 hit, otherwise this is a L1 miss.
>>
>> This patch encodes the memory level according to the specification.
>
> It's not enough. as I said it needs more fixes.
>
> For most events it should be _NA, _STORE can be only specified
> for the explicit _STORE events.
>
Yes, I forgot about that. Will re-spin the patch.

> -Andi
>
>>
>> Signed-off-by: Stephane Eranian <eranian@...gle.com>
>>
>> diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
>> index ae96cfa..81424f6 100644
>> --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
>> +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
>> @@ -114,9 +114,13 @@ static u64 precise_store_data_hsw(u64 status)
>>
>>       dse.val = 0;
>>       dse.mem_op = PERF_MEM_OP_STORE;
>> -     dse.mem_lvl = PERF_MEM_LVL_NA;
>> +     dse.mem_lvl = PERF_MEM_LVL_L1;
>> +
>>       if (status & 1)
>> -             dse.mem_lvl = PERF_MEM_LVL_L1;
>> +             dse.mem_lvl |= PERF_MEM_LVL_HIT;
>> +     else
>> +             dse.mem_lvl |= PERF_MEM_LVL_MISS;
>> +
>>       /* Nothing else supported. Sorry. */
>>       return dse.val;
>>  }
>
> --
> ak@...ux.intel.com -- Speaking for myself only
--
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