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Date: Thu, 8 May 2008 01:02:42 +0200
From: Andrea Arcangeli <andrea@qumranet.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Christoph Lameter <clameter@sgi.com>, Jack Steiner <steiner@sgi.com>,
       Robin Holt <holt@sgi.com>, Nick Piggin <npiggin@suse.de>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       kvm-devel@lists.sourceforge.net, Kanoj Sarcar <kanojsarcar@yahoo.com>,
       Roland Dreier <rdreier@cisco.com>,
       Steve Wise <swise@opengridcomputing.com>, linux-kernel@vger.kernel.org,
       Avi Kivity <avi@qumranet.com>, linux-mm@kvack.org,
       general@lists.openfabrics.org, Hugh Dickins <hugh@veritas.com>,
       Rusty Russell <rusty@rustcorp.com.au>,
       Anthony Liguori <aliguori@us.ibm.com>, Chris Wright <chrisw@redhat.com>,
       Marcelo Tosatti <marcelo@kvack.org>, Eric Dumazet <dada1@cosmosbay.com>,
       "Paul E. McKenney" <paulmck@us.ibm.com>
Subject: Re: [PATCH 08 of 11] anon-vma-rwsem
Message-ID: <20080507230242.GL8276@duo.random>
References: <6b384bb988786aa78ef0.1210170958@duo.random> <alpine.LFD.1.10.0805071349200.3024@woody.linux-foundation.org> <20080507212650.GA8276@duo.random> <alpine.LFD.1.10.0805071429170.3024@woody.linux-foundation.org> <20080507222205.GC8276@duo.random> <alpine.LFD.1.10.0805071540300.3024@woody.linux-foundation.org> <20080507225801.GK8276@duo.random>
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To remove mm_lock without adding an horrible system-wide lock before
every i_mmap_lock etc.. we've to remove
invalidate_range_begin/end. Then we can return to an older approach of
doing only invalidate_page and serializing it with the PT lock against
get_user_pages. That works fine for KVM but GRU will have to flush the
tlb once every time we drop the PT lock, that means once per each 512
ptes on x86-64 etc... instead of a single time for the whole range
regardless how large the range is.