linux-kernel - Re: [PATCH 05/10] mm, page_alloc: scale the number of pages that are batch allocated

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Message-ID: <20231011125427.dtwr2jerqzehjjxo@techsingularity.net>
Date:   Wed, 11 Oct 2023 13:54:27 +0100
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Huang Ying <ying.huang@...el.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Arjan Van De Ven <arjan@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>,
        Johannes Weiner <jweiner@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Matthew Wilcox <willy@...radead.org>,
        Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH 05/10] mm, page_alloc: scale the number of pages that are
 batch allocated

On Wed, Sep 20, 2023 at 02:18:51PM +0800, Huang Ying wrote:
> When a task is allocating a large number of order-0 pages, it may
> acquire the zone->lock multiple times allocating pages in batches.
> This may unnecessarily contend on the zone lock when allocating very
> large number of pages.  This patch adapts the size of the batch based
> on the recent pattern to scale the batch size for subsequent
> allocations.
> 
> On a 2-socket Intel server with 224 logical CPU, we tested kbuild on
> one socket with `make -j 112`.  With the patch, the cycles% of the
> spinlock contention (mostly for zone lock) decreases from 40.5% to
> 37.9% (with PCP size == 361).
> 
> Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
> Suggested-by: Mel Gorman <mgorman@...hsingularity.net>

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

-- 
Mel Gorman
SUSE Labs