linux-kernel - Re: [PATCH 1/2] mm/page_alloc: free order-0 pages through PCP in page_frag

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Message-ID: <20181105092642.GF23537@techsingularity.net>
Date:   Mon, 5 Nov 2018 09:26:42 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Aaron Lu <aaron.lu@...el.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
        "=?utf-8:iso-8859-1?B?UGF3ZcWC?= Staszewski" <pstaszewski@...are.pl>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Yoel Caspersen <yoel@...knet.dk>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH 1/2] mm/page_alloc: free order-0 pages through PCP in
 page_frag_free()

On Mon, Nov 05, 2018 at 04:58:19PM +0800, Aaron Lu wrote:
> page_frag_free() calls __free_pages_ok() to free the page back to
> Buddy. This is OK for high order page, but for order-0 pages, it
> misses the optimization opportunity of using Per-Cpu-Pages and can
> cause zone lock contention when called frequently.
> 
> [1]: https://www.spinics.net/lists/netdev/msg531362.html
> [2]: https://www.spinics.net/lists/netdev/msg531421.html
> [3]: https://www.spinics.net/lists/netdev/msg531556.html
> Reported-by: PaweÅ Staszewski <pstaszewski@...are.pl>
> Analysed-by: Jesper Dangaard Brouer <brouer@...hat.com>
> Signed-off-by: Aaron Lu <aaron.lu@...el.com>

Well spotted,

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

-- 
Mel Gorman
SUSE Labs