Message-ID: <5661F548.1010506@hpe.com>
Date: Fri, 04 Dec 2015 15:19:20 -0500
From: Waiman Long <waiman.long@hpe.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12
MIME-Version: 1.0
To: Mike Galbraith <umgwanakikbuti@gmail.com>
CC: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
        linux-kernel@vger.kernel.org, Yuyang Du <yuyang.du@intel.com>,
        Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Scott J Norton <scott.norton@hpe.com>,
        Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline
References: <1449081710-20185-1-git-send-email-Waiman.Long@hpe.com>  <1449081710-20185-3-git-send-email-Waiman.Long@hpe.com>  <1449117148.3314.5.camel@gmail.com> <56609956.3030201@hpe.com> <1449194876.3240.9.camel@gmail.com>
In-Reply-To: <1449194876.3240.9.camel@gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1140
Lines: 26

On 12/03/2015 09:07 PM, Mike Galbraith wrote:
> On Thu, 2015-12-03 at 14:34 -0500, Waiman Long wrote:
>> On 12/02/2015 11:32 PM, Mike Galbraith wrote:
>>> Is that with the box booted skew_tick=1?
>> I haven't tried that kernel parameter. I will try it to see if it can
>> improve the situation. BTW, will there be other undesirable side effects
>> of using this other than the increased power consumption as said in the
>> kernel-parameters.txt file?
> Not that are known.  I kinda doubt you'd notice the power, but you
> should see a notable performance boost.  Who knows, with a big enough
> farm of busy big boxen, it may save power by needing fewer of them.
>
> 	-Mike
>

You are right. Use skew_tick=1 did improve performance and reduce the 
overhead of clock tick processing rather significantly. I think it 
should be the default for large SMP boxes. Thanks for the tip.

Cheers,
Longman
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/