Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v3 6/7] x86/smpboot: introduce per-cpu variable for HT
 siblings
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     linux-kernel@vger.kernel.org, peterz@infradead.org,
        mingo@redhat.com, steven.sistare@oracle.com,
        dhaval.giani@oracle.com, daniel.lezcano@linaro.org,
        vincent.guittot@linaro.org, viresh.kumar@linaro.org,
        tim.c.chen@linux.intel.com, mgorman@techsingularity.net
References: <20190627012919.4341-1-subhra.mazumdar@oracle.com>
 <20190627012919.4341-7-subhra.mazumdar@oracle.com>
 <alpine.DEB.2.21.1906270844500.32342@nanos.tec.linutronix.de>
 <alpine.DEB.2.21.1906270853300.32342@nanos.tec.linutronix.de>
From:   Subhra Mazumdar <subhra.mazumdar@oracle.com>
Message-ID: <fb445f4b-e415-d92b-4ca6-f104cb5fc9cb@oracle.com>
Date:   Thu, 27 Jun 2019 18:06:47 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.5.1
MIME-Version: 1.0
In-Reply-To: <alpine.DEB.2.21.1906270853300.32342@nanos.tec.linutronix.de>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 6/26/19 11:54 PM, Thomas Gleixner wrote:
> On Thu, 27 Jun 2019, Thomas Gleixner wrote:
>
>> On Wed, 26 Jun 2019, subhra mazumdar wrote:
>>
>>> Introduce a per-cpu variable to keep the number of HT siblings of a cpu.
>>> This will be used for quick lookup in select_idle_cpu to determine the
>>> limits of search.
>> Why? The number of siblings is constant at least today unless you play
>> silly cpu hotplug games. A bit more justification for adding yet another
>> random storage would be appreciated.
>>
>>> This patch does it only for x86.
>> # grep 'This patch' Documentation/process/submitting-patches.rst
>>
>> IOW, we all know already that this is a patch and from the subject prefix
>> and the diffstat it's pretty obvious that this is x86 only.
>>
>> So instead of documenting the obvious, please add proper context to justify
>> the change.
> Aside of that the right ordering is to introduce the default fallback in a
> separate patch, which explains the reasoning and then in the next one add
> the x86 optimized version.
OK. I will also add the extra optimization for other architectures.

Thanks,
Subhra
>
> Thanks,
>
> 	tglx