linux-kernel - Re: [PATCH] mm: meminit: Finish initialisation of struct pages before basic setup

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Message-ID: <20150625213443.GA129272@asylum.americas.sgi.com>
Date:	Thu, 25 Jun 2015 16:34:43 -0500
From:	Nathan Zimmer <nzimmer@....com>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Nathan Zimmer <nzimmer@....com>,
	Daniel J Blueman <daniel@...ascale.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Waiman Long <waiman.long@...com>,
	Dave Hansen <dave.hansen@...el.com>,
	Scott Norton <scott.norton@...com>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Steffen Persvold <sp@...ascale.com>
Subject: Re: [PATCH] mm: meminit: Finish initialisation of struct pages
	before basic setup

On Thu, Jun 25, 2015 at 09:48:55PM +0100, Mel Gorman wrote:
> On Wed, Jun 24, 2015 at 05:50:28PM -0500, Nathan Zimmer wrote:
> > My apologies for taking so long to get back to this.
> > 
> > I think I did locate two potential sources of slowdown.
> > One is the set_cpus_allowed_ptr as I have noted previously.
> > However I only notice that on the very largest boxes.
> > I did cobble together a patch that seems to help.
> > 
> 
> If you are using kthread_create_on_node(), is it even necessary to call
> set_cpus_allowed_ptr() at all?
> 

Yup kthread_create_on_node unconditionanly calls
set_cpus_allowed_ptr(task, cpu_all_mask);
It does it to avoid inherting kthreadd's properties.

Not being familiar with scheduling code I assumed I missed something.
However it sounds like it should respect the choice.


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