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From: Michal Hocko <mhocko@suse.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org,
	linux-acpi@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Dave Hansen <dave.hansen@intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Wei Yang <richard.weiyang@linux.alibaba.com>,
	Oscar Salvador <osalvador@suse.de>,
	Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v1 5/5] mm/memory_hotplug: update comment regarding zone shuffling
Date: Fri, 2 Oct 2020 15:41:49 +0200
Message-ID: <20201002134149.GK4555@dhcp22.suse.cz> (raw)
In-Reply-To: <20200928182110.7050-6-david@redhat.com>

On Mon 28-09-20 20:21:10, David Hildenbrand wrote:
> As we no longer shuffle via generic_online_page() and when undoing
> isolation, we can simplify the comment.
> 
> We now effectively shuffle only once (properly) when onlining new
> memory.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Mike Rapoport <rppt@kernel.org>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/memory_hotplug.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 9db80ee29caa..c589bd8801bb 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -859,13 +859,10 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
>  	undo_isolate_page_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE);
>  
>  	/*
> -	 * When exposing larger, physically contiguous memory areas to the
> -	 * buddy, shuffling in the buddy (when freeing onlined pages, putting
> -	 * them either to the head or the tail of the freelist) is only helpful
> -	 * for maintaining the shuffle, but not for creating the initial
> -	 * shuffle. Shuffle the whole zone to make sure the just onlined pages
> -	 * are properly distributed across the whole freelist. Make sure to
> -	 * shuffle once pageblocks are no longer isolated.
> +	 * Freshly onlined pages aren't shuffled (e.g., all pages are placed to
> +	 * the tail of the freelist when undoing isolation). Shuffle the whole
> +	 * zone to make sure the just onlined pages are properly distributed
> +	 * across the whole freelist - to create an initial shuffle.
>  	 */
>  	shuffle_zone(zone);
>  
> -- 
> 2.26.2

-- 
Michal Hocko
SUSE Labs

      parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28 18:21 [PATCH v1 0/5] mm: place pages to the freelist tail when onling and undoing isolation David Hildenbrand
2020-09-28 18:21 ` [PATCH v1 1/5] mm/page_alloc: convert "report" flag of __free_one_page() to a proper flag David Hildenbrand
2020-09-28 20:11   ` Pankaj Gupta
2020-09-29  8:58   ` Wei Yang
2020-10-02 13:17   ` Michal Hocko
2020-10-02 13:41   ` Matthew Wilcox
2020-10-02 14:48     ` David Hildenbrand
2020-10-02 14:57       ` David Hildenbrand
2020-09-28 18:21 ` [PATCH v1 2/5] mm/page_alloc: place pages to tail in __putback_isolated_page() David Hildenbrand
2020-09-28 20:38   ` Pankaj Gupta
2020-09-29  9:10   ` Wei Yang
2020-10-02 13:19   ` Michal Hocko
2020-09-28 18:21 ` [PATCH v1 3/5] mm/page_alloc: always move pages to the tail of the freelist in unset_migratetype_isolate() David Hildenbrand
2020-09-28 20:55   ` Pankaj Gupta
2020-09-29  9:18   ` Wei Yang
2020-09-29 10:12     ` David Hildenbrand
2020-09-30  7:48       ` Wei Yang
2020-10-02 13:24   ` Michal Hocko
2020-10-02 15:20     ` David Hildenbrand
2020-10-05  6:56       ` Michal Hocko
2020-10-05  8:20         ` Mel Gorman
2020-10-05  9:11           ` David Hildenbrand
2020-09-28 18:21 ` [PATCH v1 4/5] mm/page_alloc: place pages to tail in __free_pages_core() David Hildenbrand
2020-09-28 20:33   ` Pankaj Gupta
2020-09-29  9:36   ` Wei Yang
2020-09-29 10:14     ` David Hildenbrand
2020-10-02 13:41   ` Michal Hocko
2020-10-02 15:10     ` David Hildenbrand
2020-09-28 18:21 ` [PATCH v1 5/5] mm/memory_hotplug: update comment regarding zone shuffling David Hildenbrand
2020-09-29  9:40   ` Wei Yang
2020-10-02 13:41   ` Michal Hocko [this message]

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