Re: specjbb2005 fails with 2.6.29-rc4

["Zhang, Yanmin" <yanmin_zhang@linux.intel.com>]

On Thu, 2009-02-12 at 09:20 +0800, Lin Ming wrote:
> On Thu, 2009-02-12 at 09:16 +0800, Lin Ming wrote:
> > specjbb2005 fails with 2.6.29-rc4 in many testing machines.
> > 
> > On a 4*4cores Tigerton machine, run specjb2005 with
> > starting_number_warehouses = 1 and ending_number_warehouses = 34.
> > It fails when warehouses=16.
> > 
> > Test with Jrockit VM fails. And it works well if OpenJDK is used
> > instead.
One difference between Jrockit and OpenJDK is Jrokit uses huge pages.

> 
> Bisect locates below commit.
> 
> > 
> > commit fc8744adc870a8d4366908221508bb113d8b72ee
> > Author: Linus Torvalds <torvalds@linux-foundation.org>
> > Date:   Sat Jan 31 15:08:56 2009 -0800
> > 
> >     Stop playing silly games with the VM_ACCOUNT flag
> >     
> >     The mmap_region() code would temporarily set the VM_ACCOUNT flag for
> >     anonymous shared mappings just to inform shmem_zero_setup() that it
> >     should enable accounting for the resulting shm object.  It would then
> >     clear the flag after calling ->mmap (for the /dev/zero case) or doing
> >     shmem_zero_setup() (for the MAP_ANON case).
> >     
> >     This just resulted in vma merge issues, but also made for just
> >     unnecessary confusion.  Use the already-existing VM_NORESERVE flag for
> >     this instead, and let shmem_{zero|file}_setup() just figure it out from
> >     that.
> >     
> >     This also happens to make it obvious that the new DRI2 GEM layer uses a
> >     non-reserving backing store for its object allocation - which is quite
> >     possibly not intentional.  But since I didn't want to change semantics
> >     in this patch, I left it alone, and just updated the caller to use the
> >     new flag semantics.
> >     
> >     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> > ---
> >  drivers/gpu/drm/drm_gem.c |    2 +-
> >  ipc/shm.c                 |    4 +-
> >  mm/mmap.c                 |   48 +++++++++++++++++++++++---------------------
> >  mm/shmem.c                |    2 +-
> >  4 files changed, 29 insertions(+), 27 deletions(-)
> > 
>