From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Arcangeli <andrea@qumranet.com>,
Christoph Lameter <clameter@sgi.com>,
Andrew Morton <akpm@linux-foundation.org>,
steiner@sgi.com, holt@sgi.com, npiggin@suse.de,
kvm-devel@lists.sourceforge.net, kanojsarcar@yahoo.com,
rdreier@cisco.com, swise@opengridcomputing.com,
linux-kernel@vger.kernel.org, avi@qumranet.com,
linux-mm@kvack.org, general@lists.openfabrics.org,
hugh@veritas.com, rusty@rustcorp.com.au, aliguori@us.ibm.com,
chrisw@redhat.com, marcelo@kvack.org, dada1@cosmosbay.com,
paulmck@us.ibm.com
Subject: Re: [PATCH 08 of 11] anon-vma-rwsem
Date: Fri, 09 May 2008 20:37:29 +0200 [thread overview]
Message-ID: <1210358249.13978.275.camel@twins> (raw)
In-Reply-To: <alpine.LFD.1.10.0805080907420.3024@woody.linux-foundation.org>
On Thu, 2008-05-08 at 09:11 -0700, Linus Torvalds wrote:
>
> On Thu, 8 May 2008, Linus Torvalds wrote:
> >
> > Also, we'd need to make it
> >
> > unsigned short flag:1;
> >
> > _and_ change spinlock_types.h to make the spinlock size actually match the
> > required size (right now we make it an "unsigned int slock" even when we
> > actually only use 16 bits).
>
> Btw, this is an issue only on 32-bit x86, because on 64-bit one we already
> have the padding due to the alignment of the 64-bit pointers in the
> list_head (so there's already empty space there).
>
> On 32-bit, the alignment of list-head is obviously just 32 bits, so right
> now the structure is "perfectly packed" and doesn't have any empty space.
> But that's just because the spinlock is unnecessarily big.
>
> (Of course, if anybody really uses NR_CPUS >= 256 on 32-bit x86, then the
> structure really will grow. That's a very odd configuration, though, and
> not one I feel we really need to care about).
Another possibility, would something like this work?
/*
* null out the begin function, no new begin calls can be made
*/
rcu_assing_pointer(my_notifier.invalidate_start_begin, NULL);
/*
* lock/unlock all rmap locks in any order - this ensures that any
* pending start() will have its end() function called.
*/
mm_barrier(mm);
/*
* now that no new start() call can be made and all start()/end() pairs
* are complete we can remove the notifier.
*/
mmu_notifier_remove(mm, my_notifier);
This requires a mmu_notifier instance per attached mm and that
__mmu_notifier_invalidate_range_start() uses rcu_dereference() to obtain
the function.
But I think its enough to ensure that:
for each start an end will be called
It can however happen that end is called without start - but we could
handle that I think.
next prev parent reply other threads:[~2008-05-09 18:37 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-07 14:35 [PATCH 00 of 11] mmu notifier #v16 Andrea Arcangeli
2008-05-07 14:35 ` [PATCH 01 of 11] mmu-notifier-core Andrea Arcangeli
2008-05-07 17:35 ` Rik van Riel
2008-05-07 20:02 ` Andrew Morton
2008-05-07 20:05 ` Andrew Morton
2008-05-07 20:30 ` Linus Torvalds
2008-05-07 21:58 ` Andrea Arcangeli
2008-05-07 22:11 ` Linus Torvalds
2008-05-07 22:27 ` Andrea Arcangeli
2008-05-07 22:31 ` [ofa-general] " Roland Dreier
2008-05-07 22:39 ` Andrea Arcangeli
2008-05-07 23:03 ` Linus Torvalds
2008-05-07 22:37 ` Andrea Arcangeli
2008-05-07 23:38 ` Linus Torvalds
2008-05-07 23:00 ` Linus Torvalds
2008-05-07 14:35 ` [PATCH 02 of 11] get_task_mm Andrea Arcangeli
2008-05-07 15:59 ` Robin Holt
2008-05-07 16:20 ` Andrea Arcangeli
2008-05-07 14:35 ` [PATCH 03 of 11] invalidate_page outside PT lock Andrea Arcangeli
2008-05-07 17:39 ` Rik van Riel
2008-05-07 17:57 ` Andrea Arcangeli
2008-05-07 14:35 ` [PATCH 04 of 11] free-pgtables Andrea Arcangeli
2008-05-07 17:41 ` Rik van Riel
2008-05-07 14:35 ` [PATCH 05 of 11] unmap vmas tlb flushing Andrea Arcangeli
2008-05-07 17:46 ` Rik van Riel
2008-05-07 14:35 ` [PATCH 06 of 11] rwsem contended Andrea Arcangeli
2008-05-07 14:35 ` [PATCH 07 of 11] i_mmap_rwsem Andrea Arcangeli
2008-05-07 14:35 ` [PATCH 08 of 11] anon-vma-rwsem Andrea Arcangeli
2008-05-07 20:56 ` Linus Torvalds
2008-05-07 21:26 ` Andrea Arcangeli
2008-05-07 21:36 ` Linus Torvalds
2008-05-07 22:22 ` Andrea Arcangeli
2008-05-07 22:31 ` Andrew Morton
2008-05-07 22:44 ` Andrea Arcangeli
2008-05-07 22:59 ` Andrew Morton
2008-05-07 23:19 ` Linus Torvalds
2008-05-07 23:39 ` Christoph Lameter
2008-05-08 0:03 ` Linus Torvalds
2008-05-08 0:52 ` Robin Holt
2008-05-08 0:56 ` Christoph Lameter
2008-05-08 1:07 ` Linus Torvalds
2008-05-08 1:39 ` Linus Torvalds
2008-05-08 1:52 ` Andrea Arcangeli
2008-05-08 1:57 ` Linus Torvalds
2008-05-08 2:24 ` Andrea Arcangeli
2008-05-08 2:32 ` Linus Torvalds
2008-05-07 23:39 ` Andrea Arcangeli
2008-05-08 1:02 ` Linus Torvalds
2008-05-08 1:12 ` Christoph Lameter
2008-05-08 1:32 ` Linus Torvalds
2008-05-08 2:56 ` Andrea Arcangeli
2008-05-08 3:10 ` Christoph Lameter
2008-05-08 3:41 ` Andrea Arcangeli
2008-05-08 4:14 ` Linus Torvalds
2008-05-08 5:20 ` Andrea Arcangeli
2008-05-08 5:27 ` Pekka Enberg
2008-05-08 5:30 ` Pekka Enberg
2008-05-08 5:49 ` Andrea Arcangeli
2008-05-08 15:03 ` Linus Torvalds
2008-05-08 16:11 ` Linus Torvalds
2008-05-08 22:01 ` Andrea Arcangeli
2008-05-09 18:37 ` Peter Zijlstra [this message]
2008-05-09 18:55 ` Andrea Arcangeli
2008-05-09 19:04 ` Peter Zijlstra
2008-05-08 1:26 ` Andrea Arcangeli
2008-05-07 23:28 ` Benjamin Herrenschmidt
2008-05-07 23:45 ` Andrea Arcangeli
2008-05-08 1:34 ` Andrea Arcangeli
2008-05-13 12:14 ` Nick Piggin
2008-05-14 5:43 ` Benjamin Herrenschmidt
2008-05-14 6:06 ` Nick Piggin
2008-05-14 13:15 ` Jack Steiner
2008-05-07 22:44 ` Linus Torvalds
2008-05-07 22:58 ` Andrea Arcangeli
2008-05-07 23:02 ` Andrea Arcangeli
2008-05-07 23:09 ` Linus Torvalds
2008-05-08 0:38 ` Robin Holt
2008-05-08 0:55 ` Linus Torvalds
2008-05-13 12:06 ` Nick Piggin
2008-05-13 15:32 ` Robin Holt
2008-05-14 4:11 ` Nick Piggin
2008-05-14 11:26 ` Robin Holt
2008-05-14 15:18 ` Linus Torvalds
2008-05-14 16:22 ` Robin Holt
2008-05-14 16:56 ` Linus Torvalds
2008-05-14 17:57 ` Christoph Lameter
2008-05-14 18:27 ` Linus Torvalds
2008-05-17 1:38 ` mm notifier: Notifications when pages are unmapped Christoph Lameter
2008-05-15 7:57 ` [PATCH 08 of 11] anon-vma-rwsem Nick Piggin
2008-05-15 11:01 ` Robin Holt
2008-05-15 11:12 ` Avi Kivity
2008-05-15 17:33 ` Christoph Lameter
2008-05-15 23:52 ` Nick Piggin
2008-05-16 11:23 ` Robin Holt
2008-05-16 11:50 ` Robin Holt
2008-05-20 5:31 ` Nick Piggin
2008-05-20 10:01 ` Robin Holt
2008-05-20 10:50 ` Nick Piggin
2008-05-20 11:05 ` Robin Holt
2008-05-20 11:14 ` Nick Piggin
2008-05-20 11:26 ` Robin Holt
2008-05-07 22:42 ` Jack Steiner
2008-05-07 14:35 ` [PATCH 09 of 11] mm_lock-rwsem Andrea Arcangeli
2008-05-07 14:36 ` [PATCH 10 of 11] export zap_page_range for XPMEM Andrea Arcangeli
2008-05-07 14:36 ` [PATCH 11 of 11] mmap sems Andrea Arcangeli
-- strict thread matches above, loose matches on Subject: below --
2008-05-02 15:05 [PATCH 00 of 11] mmu notifier #v15 Andrea Arcangeli
2008-05-02 15:05 ` [PATCH 08 of 11] anon-vma-rwsem Andrea Arcangeli
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