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Date:   Wed, 21 Apr 2021 08:40:47 +0100
From:   Mel Gorman <mgorman@suse.de>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Peter Xu <peterx@redhat.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Matthew Wilcox <willy@infradead.org>,
        Will Deacon <will@kernel.org>,
        Michel Lespinasse <walken@google.com>,
        Arjun Roy <arjunroy@google.com>,
        Huang Ying <ying.huang@intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH -V3] NUMA balancing: reduce TLB flush via delaying
 mapping on hint page fault
Message-ID: <20210421074047.GD15768@suse.de>
References: <20210408132236.1175607-1-ying.huang@intel.com>
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In-Reply-To: <20210408132236.1175607-1-ying.huang@intel.com>
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On Thu, Apr 08, 2021 at 09:22:36PM +0800, Huang Ying wrote:
> With NUMA balancing, in hint page fault handler, the faulting page
> will be migrated to the accessing node if necessary.  During the
> migration, TLB will be shot down on all CPUs that the process has run
> on recently.  Because in the hint page fault handler, the PTE will be
> made accessible before the migration is tried.  The overhead of TLB
> shooting down can be high, so it's better to be avoided if possible.
> In fact, if we delay mapping the page until migration, that can be
> avoided.  This is what this patch doing.
> 

<SNIP>

> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Reviewed-by: Mel Gorman <mgorman@suse.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: "Matthew Wilcox" <willy@infradead.org>
> Cc: Will Deacon <will@kernel.org>
> Cc: Michel Lespinasse <walken@google.com>
> Cc: Arjun Roy <arjunroy@google.com>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

Hi Andrew,

I do not see this in the mmots tree. Was something missed in this patch
that needs fixing or did it just fall through the cracks?

Thanks.

-- 
Mel Gorman
SUSE Labs