linux-kernel - Re: [PATCH -V11 2/9] mm/migrate: update node demotion order on hotplug events

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Message-ID: <4d3c777e-20bd-b1f2-12ba-6af9d08cca45@intel.com>
Date:   Thu, 24 Feb 2022 16:49:43 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Abhishek Goel <huntbag@...ux.vnet.ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Zi Yan <ziy@...dia.com>, David Hildenbrand <david@...hat.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Huang Ying <ying.huang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH -V11 2/9] mm/migrate: update node demotion order on
 hotplug events

On 2/24/22 15:37, Abhishek Goel wrote:
> 
> On 24/02/22 05:35, Dave Hansen wrote:
>> On 2/23/22 15:02, Abhishek Goel wrote:
>>> If needed, I will provide experiment results and traces that were used
>>> to conclude this.
>> It would be great if you can provide some more info.  Even just a CPU
>> time profile would be helpful.
> 
> Average total time taken for SMT=8 to SMT=1 in v5.14 : 20s
> 
> Average total time taken for SMT=8 to SMT=1 in v5.15 : 36s
> 
> (Observed in system with 150+ CPUs )

I was kinda thinking of:

	perf record / perf report

output.  Not wall clock time.  We need to know what the kernel is doing
during those extra 16 seconds.