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Date:   Tue, 1 Oct 2019 15:08:24 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc:     David Hildenbrand <david@redhat.com>,
        Alexander Duyck <alexander.duyck@gmail.com>,
        virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org,
        dave.hansen@intel.com, linux-kernel@vger.kernel.org,
        willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org, mgorman@techsingularity.net,
        vbabka@suse.cz, osalvador@suse.de, yang.zhang.wz@gmail.com,
        pagupta@redhat.com, konrad.wilk@oracle.com, nitesh@redhat.com,
        riel@surriel.com, lcapitulino@redhat.com, wei.w.wang@intel.com,
        aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com
Subject: Re: [PATCH v11 0/6] mm / virtio: Provide support for unused page
 reporting
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On Tue, Oct 01, 2019 at 09:21:46AM -0700, Alexander Duyck wrote:
> I thought what Michal was asking for was what was the benefit of using the
> boundary pointer. I added a bit up above and to the description for patch
> 3 as on a 32G VM it adds up to about a 18% difference without factoring in
> the page faulting and zeroing logic that occurs when we actually do the
> madvise.

Something maybe worth adding to the log:

one disadvantage of the tight integration with the mm core is
that only a single reporting device is supported.
It's not obvious that more than one is useful though.

-- 
MST