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Date: Fri, 27 Mar 2015 12:23:49 +0800
From: Wanpeng Li <wanpeng.li@linux.intel.com>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: peterz@infradead.org, mingo@kernel.org, riel@redhat.com,
        daniel.lezcano@linaro.org, vincent.guittot@linaro.org,
        srikar@linux.vnet.ibm.com, pjt@google.com, benh@kernel.crashing.org,
        efault@gmx.de, linux-kernel@vger.kernel.org, iamjoonsoo.kim@lge.com,
        svaidy@linux.vnet.ibm.com, tim.c.chen@linux.intel.com,
        morten.rasmussen@arm.com, jason.low2@hp.com,
        Wanpeng Li <wanpeng.li@linux.intel.com>
Subject: Re: [PATCH V2] sched: Improve load balancing in the presence of idle
 CPUs
Message-ID: <20150327042349.GA4950@kernel>
Reply-To: Wanpeng Li <wanpeng.li@linux.intel.com>
References: <20150326130014.21532.17158.stgit@preeti.in.ibm.com>
 <20150327021201.GA4491@kernel>
 <5514DD91.8090505@linux.vnet.ibm.com>
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Hi Preeti,
On Fri, Mar 27, 2015 at 10:03:21AM +0530, Preeti U Murthy wrote:
>is set to CPU_NOT_IDLE.
>
>""
>idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
>
>And,
>
>When nohz_idle_balance() is called, the state of idle of ILB CPU is
>checked before proceeding with load balancing on idle CPUs.
>
>""
>
>if (idle != CPU_IDLE ||
>             !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
>                 goto end;
>

This idle is the one caculated in run_rebalance_domains() before invoke 
rebalance_domains(), rebalance_domains() cannot modify this local
variable.

Regards,
Wanpeng Li 

>You see that nohz idle balancing gets aborted.
>
>Regards
>Preeti U Murthy
>
>
>
>> 
>> Regards,
>> Wanpeng Li 
>>