linux-kernel - Re: [PATCH V6 08/13] perf: Add Sandy Bridge-EP uncore support

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Date:	Tue, 19 Jun 2012 09:18:09 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	"Yan, Zheng" <zheng.z.yan@...el.com>
Cc:	a.p.zijlstra@...llo.nl, mingo@...e.hu, jolsa@...hat.com,
	andi@...stfloor.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V6 08/13] perf: Add Sandy Bridge-EP uncore support

On Tue, Jun 19, 2012 at 2:59 AM, Yan, Zheng <zheng.z.yan@...el.com> wrote:
> On 06/18/2012 11:28 PM, Stephane Eranian wrote:
>> On Fri, Jun 15, 2012 at 8:31 AM, Yan, Zheng <zheng.z.yan@...el.com> wrote:
>>> > From: "Yan, Zheng" <zheng.z.yan@...el.com>
>>> >
>>> > Add Intel Nehalem and Sandy Bridge uncore pmu support. The uncore
>>> > subsystem in Sandy Bridge-EP consists of 8 components (Ubox,
>>> > Cacheing Agent, Home Agent, Memory controller, Power Control,
>>> > QPI Link Layer, R2PCIe, R3QPI).
>>> >
>> I did not find in this patch the support for the C-Box Filter register
>> (SNBEP_C0_MSR_PMON_BOX_FILTER). Based on the description
>> in the manual, looks like a valuable filter to support, especially for
>> the core/thread filtering capability.
>>
>> There is only one such filter per box, and it can be used by any events.
>> So looks like we have another offcore_resp style register to manage
>> here. Need to ensure the value of that filter is shared by all 4 counters.
>> If you were to support that, you'd have to enable the tid filter on the
>> CBox config regs and export that via sysfs. Also I assume you'd
>> pass the value of that filter either in config1 or in the upper 32 bits
>> of the config reg.
>>
>> What's your take on that?
>>
>
> I'm working on uncore support for Nehalem-EX which has extensive use of
> shared extra registers. Once that work done, adding C-Box filter support
> should be easy.
>
Ok. Note that the code logic to handle shared regs is already there and is
used for OFFCORE_RSP*, LBR_SELECT and LD_LAT (soon). Would be
nice to reuse that framework for this as well. Though I understand you're
looking at per box sharing as opposed to per physical core sharing or
cross HT sharing.

> Regards
> Yan, Zheng
>
>
>
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