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

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Message-ID: <20140515143258.GA19657@tassilo.jf.intel.com>
Date:	Thu, 15 May 2014 07:32:58 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	acme@...stprotocols.net, jolsa@...hat.com, jmario@...hat.com,
	dzickus@...hat.com
Subject: Re: [PATCH] perf/x86: fix Haswell precise store data source encoding

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.

-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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