Re: [PATCH 1/4] VM/RMAP: Add infrastructure for batching the rmap chain locking v2

[Andi Kleen <andi@firstfloor.org>]

On Wed, May 18, 2011 at 01:25:47PM -0700, Andrew Morton wrote:
> On Fri, 13 May 2011 16:46:21 -0700
> Andi Kleen <andi@firstfloor.org> wrote:
> 
> > In fork and exit it's quite common to take same rmap chain locks
> > again and again when the whole address space is processed  for a
> > address space that has a lot of sharing. Also since the locking
> > has changed to always lock the root anon_vma this can be very
> > contended.
> > 
> > This patch adds a simple wrapper to batch these lock acquisitions
> > and only reaquire the lock when another is needed. The main
> > advantage is that when multiple processes are doing this in
> > parallel they will avoid a lot of communication overhead
> > on the lock cache line.
> > 
> > v2: Address review feedback. Drop lockbreak. Rename init function.
> 
> Doesn't compile:
> 
> include/linux/rmap.h: In function 'anon_vma_unlock_batch':
> include/linux/rmap.h:146: error: 'struct anon_vma' has no member named 'lock'
> mm/rmap.c: In function '__anon_vma_lock_batch':
> mm/rmap.c:1737: error: 'struct anon_vma' has no member named 'lock'
> mm/rmap.c:1739: error: 'struct anon_vma' has no member named 'lock'
> 
> I think I reported this against the v1 patches.

Hmm is that against -mm? Which tree exactly?

Both in Linus' latest and in -next I have

include/linux/rmap.h:

struct anon_vma {
        struct anon_vma *root;  /* Root of this anon_vma tree */
        spinlock_t lock;        /* Serialize access to vma list */

So it should compile. And it compiles here of course.

To be honest I forgot where the -mm tree is, so I can't check. 
It's not in its old place on kernel.org anymore?

I'll look into checkpatch.

-Andi

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