linux-kernel - Re: [PATCH] perf,x86: add constraint for IVB CYCLE_ACTIVITY:CYCLES_LDM

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Message-ID: <CABPqkBS3HvEGENHF0dKpOwhbQx0GBz4sT_PNFrXjxo4hYtEFtw@mail.gmail.com>
Date:	Wed, 11 Sep 2013 18:55:28 +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>,
	"Yan, Zheng" <zheng.z.yan@...el.com>,
	David Sharp <dhsharp@...gle.com>
Subject: Re: [PATCH] perf,x86: add constraint for IVB CYCLE_ACTIVITY:CYCLES_LDM_PENDING

On Wed, Sep 11, 2013 at 6:50 PM, Andi Kleen <ak@...ux.intel.com> wrote:
> On Wed, Sep 11, 2013 at 08:22:22AM -0700, Stephane Eranian wrote:
>>
>> The IvyBridge event CYCLE_ACTIVITY:CYCLES_LDM_PENDING can only
>> be measured on counters 0-3 when HT is off. When HT is on, you
>> only have counters 0-3.
>>
>> If you program it on the eight counters for 1s on a 3GHz
>> IVB laptop running a noploop, you see:
>>
>>            2 747 527 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>            2 747 527 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>            2 747 527 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>            2 747 527 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>        3 280 563 608 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>        3 280 563 608 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>        3 280 563 608 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>        3 280 563 608 CYCLE_ACTIVITY:CYCLES_LDM_PENDING
>>
>> Clearly the last 4 values are bogus.
>
> Thanks looks good.
>
> Likely need it on Haswell too?
>
Will check on that one later this week.
But I think you are right.

> -Andi
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