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From: Vlastimil Babka <vbabka@suse.cz>
To: David Hildenbrand <david@redhat.com>, linux-kernel@vger.kernel.org
Cc: 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>,
	Matthew Wilcox <willy@infradead.org>,
	Oscar Salvador <osalvador@suse.de>,
	Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
	Wei Yang <richard.weiyang@linux.alibaba.com>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Michal Hocko <mhocko@kernel.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Mike Rapoport <rppt@kernel.org>,
	Scott Cheloha <cheloha@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [PATCH v2 3/5] mm/page_alloc: move pages to tail in move_to_free_list()
Date: Tue, 20 Oct 2020 19:20:22 +0200	[thread overview]
Message-ID: <505935d6-90d2-3fce-57f0-5946968d6372@suse.cz> (raw)
In-Reply-To: <20201005121534.15649-4-david@redhat.com>

On 10/5/20 2:15 PM, David Hildenbrand wrote:
> Whenever we move pages between freelists via move_to_free_list()/
> move_freepages_block(), we don't actually touch the pages:
> 1. Page isolation doesn't actually touch the pages, it simply isolates
>     pageblocks and moves all free pages to the MIGRATE_ISOLATE freelist.
>     When undoing isolation, we move the pages back to the target list.
> 2. Page stealing (steal_suitable_fallback()) moves free pages directly
>     between lists without touching them.
> 3. reserve_highatomic_pageblock()/unreserve_highatomic_pageblock() moves
>     free pages directly between freelists without touching them.
> 
> We already place pages to the tail of the freelists when undoing isolation
> via __putback_isolated_page(), let's do it in any case (e.g., if order <=
> pageblock_order) and document the behavior. To simplify, let's move the
> pages to the tail for all move_to_free_list()/move_freepages_block() users.
> 
> In 2., the target list is empty, so there should be no change. In 3.,
> we might observe a change, however, highatomic is more concerned about
> allocations succeeding than cache hotness - if we ever realize this
> change degrades a workload, we can special-case this instance and add a
> proper comment.
> 
> This change results in all pages getting onlined via online_pages() to
> be placed to the tail of the freelist.
> 
> Reviewed-by: Oscar Salvador <osalvador@suse.de>
> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
> Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>


  parent reply	other threads:[~2020-10-20 17:20 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-05 12:15 [PATCH v2 0/5] mm: place pages to the freelist tail when onlining and undoing isolation David Hildenbrand
2020-10-05 12:15 ` [PATCH v2 1/5] mm/page_alloc: convert "report" flag of __free_one_page() to a proper flag David Hildenbrand
2020-10-05 12:15 ` [PATCH v2 2/5] mm/page_alloc: place pages to tail in __putback_isolated_page() David Hildenbrand
2020-10-20 17:18   ` Vlastimil Babka
2020-10-05 12:15 ` [PATCH v2 3/5] mm/page_alloc: move pages to tail in move_to_free_list() David Hildenbrand
2020-10-06 12:12   ` Michal Hocko
2020-10-20 17:20   ` Vlastimil Babka [this message]
2020-10-05 12:15 ` [PATCH v2 4/5] mm/page_alloc: place pages to tail in __free_pages_core() David Hildenbrand
2021-09-07 22:40   ` Sean Anderson
2021-09-08  6:21     ` David Hildenbrand
2021-09-10 23:06       ` Sean Anderson
2020-10-05 12:15 ` [PATCH v2 5/5] mm/memory_hotplug: update comment regarding zone shuffling David Hildenbrand
2020-10-20 17:21   ` Vlastimil Babka
2020-10-21 10:58   ` Pankaj Gupta

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