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Subject: Re: [PATCH v4 3/3] mm/free_pcppages_bulk: prefetch buddy while not
 holding lock
References: <20180301062845.26038-1-aaron.lu@intel.com>
 <20180301062845.26038-4-aaron.lu@intel.com>
 <20180301140044.GK15057@dhcp22.suse.cz>
 <cb158b3d-c992-6679-24df-b37d2bb170e0@suse.cz>
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <2433e857-fea7-9af4-d124-538ad17de454@intel.com>
Date: Fri, 2 Mar 2018 10:00:24 -0800
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To: Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@kernel.org>, Aaron Lu <aaron.lu@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Huang Ying <ying.huang@intel.com>, Kemi Wang <kemi.wang@intel.com>, Tim Chen <tim.c.chen@linux.intel.com>, Andi Kleen <ak@linux.intel.com>, Mel Gorman <mgorman@techsingularity.net>, Matthew Wilcox <willy@infradead.org>, David Rientjes <rientjes@google.com>

On 03/02/2018 09:55 AM, Vlastimil Babka wrote:
> It's even stranger to me. Struct page is 64 bytes these days, exactly a
> a cache line. Unless that changed, Intel CPUs prefetched a "buddy" cache
> line (that forms an aligned 128 bytes block with the one we touch).

I believe that was a behavior that was specific to the Pentium 4
"Netburst" era.  I don't think the 128-byte line behavior exists on
modern Intel cpus.

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