linux-kernel - Re: [RFC 3/5] mm, page_alloc(): remove setup

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Date:   Thu, 10 Sep 2020 11:23:07 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Michal Hocko <mhocko@...nel.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        David Hildenbrand <david@...hat.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [RFC 3/5] mm, page_alloc(): remove setup_pageset()

On Mon, Sep 07, 2020 at 06:36:26PM +0200, Vlastimil Babka wrote:
> We initialize boot-time pagesets with setup_pageset(), which sets high and
> batch values that effectively disable pcplists.
> 
> We can remove this wrapper if we just set these values for all pagesets in
> pageset_init(). Non-boot pagesets then subsequently update them to specific
> values.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>

Reviewed-by: Oscar Salvador <osalvador@...e.de>

Just one question below:

> -static void setup_pageset(struct per_cpu_pageset *p)
> -{
> -	pageset_init(p);
> -	pageset_update(&p->pcp, 0, 1);
> +	/*
> +	 * Set batch and high values safe for a boot pageset. Proper pageset's
> +	 * initialization will update them.
> +	 */
> +	pcp->high = 0;
> +	pcp->batch  = 1;

pageset_update was manipulating these values with barriers in between.
I guess we do not care here because we are not really updating but
initializing them, right?

-- 
Oscar Salvador
SUSE L3