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Date: Wed, 7 May 2014 09:21:03 -0700
Message-ID: <CA+55aFysZyb1N9sC6ieRYbfGO6ATXT2eAe0-RbWcUoCHko8gFw@mail.gmail.com>
Subject: Re: [RFC] Heterogeneous memory management (mirror process address
 space on a device mmu).
From: Linus Torvalds <torvalds@linux-foundation.org>
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To: Davidlohr Bueso <davidlohr@hp.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Jerome Glisse <j.glisse@gmail.com>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Mel Gorman <mgorman@suse.de>, "H. Peter Anvin" <hpa@zytor.com>, Andrew Morton <akpm@linux-foundation.org>, Linda Wang <lwang@redhat.com>, Kevin E Martin <kem@redhat.com>, Jerome Glisse <jglisse@redhat.com>, Andrea Arcangeli <aarcange@redhat.com>, Johannes Weiner <jweiner@redhat.com>, Larry Woodman <lwoodman@redhat.com>, Rik van Riel <riel@redhat.com>, Dave Airlie <airlied@redhat.com>, Jeff Law <law@redhat.com>, Brendan Conoboy <blc@redhat.com>, Joe Donohue <jdonohue@redhat.com>, Duncan Poole <dpoole@nvidia.com>, Sherry Cheung <SCheung@nvidia.com>, Subhash Gutti <sgutti@nvidia.com>, John Hubbard <jhubbard@nvidia.com>, Mark Hairgrove <mhairgrove@nvidia.com>, Lucien Dunning <ldunning@nvidia.com>, Cameron Buschardt <cabuschardt@nvidia.com>, Arvind Gopalakrishnan <arvindg@nvidia.com>, Haggai Eran <haggaie@mellanox.com>, Or Gerlitz <ogerlitz@mellanox.com>, Sagi Grimberg <sagig@mellanox.com>, Shachar Raindel <raindel@mellanox.com>, Liran Liss <liranl@mellanox.com>, Roland Dreier <roland@purestorage.com>, "Sander, Ben" <ben.sander@amd.com>, "Stoner, Greg" <Greg.Stoner@amd.com>, "Bridgman, John" <John.Bridgman@amd.com>, "Mantor, Michael" <Michael.Mantor@amd.com>, "Blinzer, Paul" <Paul.Blinzer@amd.com>, "Morichetti, Laurent" <Laurent.Morichetti@amd.com>, "Deucher, Alexander" <Alexander.Deucher@amd.com>, "Gabbay, Oded" <Oded.Gabbay@amd.com>

On Tue, May 6, 2014 at 7:33 PM, Davidlohr Bueso <davidlohr@hp.com> wrote:
=>
> What is perhaps not so obvious is that rwsem+optimistic spinning beats
> all others, including the improved qrwlock from Waiman and Peter. This
> is mostly because of the idea of cancelable MCS, which was mimic'ed from
> mutexes. The delta in most cases is around +10-15%, which is non
> trivial.

Ahh, excellent news. That way I don't have to worry about the anonvma
lock any more. I'll just forget about it right now, in fact.

          Linus

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