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Date: Thu, 28 Jan 2016 13:42:09 +0100
From: Borislav Petkov <bp@alien8.de>
To: Huang Rui <ray.huang@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Thomas Gleixner <tglx@linutronix.de>, Robert Richter <rric@kernel.org>,
        Jacob Shin <jacob.w.shin@gmail.com>,
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        =?utf-8?B?RnLDqWTDqXJpYw==?= Weisbecker <fweisbec@gmail.com>,
        linux-kernel@vger.kernel.org, spg_linux_kernel@amd.com, x86@kernel.org,
        Guenter Roeck <linux@roeck-us.net>,
        Andreas Herrmann <herrmann.der.user@googlemail.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>,
        Fengguang Wu <fengguang.wu@intel.com>, Aaron Lu <aaron.lu@intel.com>
Subject: Re: [PATCH v4] perf/x86/amd/power: Add AMD accumulated power
 reporting mechanism
Message-ID: <20160128124209.GC14274@pd.tnic>
References: <1453963131-2013-1-git-send-email-ray.huang@amd.com>
 <20160128090314.GB14274@pd.tnic>
 <20160128100141.GA28282@hr-amur2>
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On Thu, Jan 28, 2016 at 06:01:43PM +0800, Huang Rui wrote:
> For example: Carrizo has four CPU cores and two compute units (CUs).
> CPU0 and CPU1 belongs to CU0, CPU2 and CPU3 belongs to CU1.
> 
> At normal initialization, cpu_mask should be "0,2". That means OS
> choose CPU0 in CU0 and CPU2 in CU1 to measure the CU0 and CU1's power
> consumption. If we make the CPU2 offline at runtime, OS need try to
> find another CPU in same compute unit (Here is CU1, only CPU3 can be
> picked). Then OS will move on to the CPU3 to measure CU1's power
> consumption instead of CPU2.

So basically you want to simply say:

"Find another CPU on the same compute unit and set it in the mask of
CPUs on which we do the measurements."

Which reminds me: that cpu_mask thing is insufficiently named - it
should be called measuring_cpus_mask or so.

Btw, the kbuild robot errors come from the fact that there are changes
to cpufeature.h which I didn't mention when applying your patches. So
I've pushed the whole pile here:

http://git.kernel.org/cgit/linux/kernel/git/bp/bp.git/log/?h=tip-perf

Please use that branch instead.

Thanks.

-- 
Regards/Gruss,
    Boris.

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