From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work
Date: Mon, 5 Nov 2018 17:29:55 -0800
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References: <20181105165558.11698-1-daniel.m.jordan@oracle.com>
 <20181105172931.GP4361@dhcp22.suse.cz>
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Cc: Daniel Jordan <daniel.m.jordan@oracle.com>, linux-mm@kvack.org,
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        aarcange@redhat.com, aaron.lu@intel.com, akpm@linux-foundation.org,
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        steven.sistare@oracle.com, tim.c.chen@intel.com, tj@kernel.org,
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To: Michal Hocko <mhocko@kernel.org>
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On Mon, Nov 05, 2018 at 06:29:31PM +0100, Michal Hocko wrote:
> On Mon 05-11-18 11:55:45, 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.
> 
> I have only glanced through the documentation patch and it looks like it
> will be much less disruptive than the previous attempts. Now the obvious
> question is how does this behave on a moderately or even busy system
> when you compare that to a single threaded execution. Some numbers about
> best/worst case execution would be really helpful.

Patches 4 and 5 have some numbers where a ktask and non-ktask workload compete
against each other.  Those show either 8 ktask threads on 8 CPUs (worst case) or no ktask threads (best case).

By single threaded execution, I guess you mean 1 ktask thread.  I'll run the
experiments that way too and post the numbers.

> I will look closer later.

Great!  Thanks for your comment.

Daniel