linux-kernel - Re: [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work

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Message-ID: <20181130191819.GJ2509588@devbig004.ftw2.facebook.com>
Date:   Fri, 30 Nov 2018 11:18:19 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Daniel Jordan <daniel.m.jordan@...cle.com>
Cc:     linux-mm@...ck.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, aarcange@...hat.com,
        aaron.lu@...el.com, akpm@...ux-foundation.org,
        alex.williamson@...hat.com, bsd@...hat.com,
        darrick.wong@...cle.com, dave.hansen@...ux.intel.com,
        jgg@...lanox.com, jwadams@...gle.com, jiangshanlai@...il.com,
        mhocko@...nel.org, mike.kravetz@...cle.com,
        Pavel.Tatashin@...rosoft.com, prasad.singamsetty@...cle.com,
        rdunlap@...radead.org, steven.sistare@...cle.com,
        tim.c.chen@...el.com, vbabka@...e.cz
Subject: Re: [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work

Hello,

On Mon, Nov 05, 2018 at 11:55:45AM -0500, Daniel Jordan wrote:
> Michal, you mentioned that ktask should be sensitive to CPU utilization[1].
> ktask threads now run at the lowest priority on the system to avoid disturbing
> busy CPUs (more details in patches 4 and 5).  Does this address your concern?
> The plan to address your other comments is explained below.

Have you tested what kind of impact this has on bandwidth of a system
in addition to latency?  The thing is while this would make a better
use of a system which has idle capacity, it does so by doing more
total work.  It'd be really interesting to see how this affects
bandwidth of a system too.

Thanks.

-- 
tejun