| Message ID | 22c2ebcfe72f4f17be6d284d922895cec34e23fc.1492606297.git.christophe.leroy@c-s.fr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e8de85ca32f572f5dee00733022d8a1ce87aed3d |
| Headers | show |
Christophe Leroy <christophe.leroy@c-s.fr> writes: > Function store_updates_sp() checks whether the faulting > instruction is a store updating r1. Therefore we can limit its calls > to stores exceptions. > > This patch is an improvement of commit a7a9dcd882a67 ("powerpc: Avoid > taking a data miss on every userspace instruction miss") > > With the same microbenchmark app, run with 500 as argument, on an > MPC885 we get: > > Before this patch: 152000 DTLB misses > After this patch: 147000 DTLB misses > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> > --- > arch/powerpc/mm/fault.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > index 3a7d580fdc59..67fefb59d40e 100644 > --- a/arch/powerpc/mm/fault.c > +++ b/arch/powerpc/mm/fault.c > @@ -287,7 +287,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, > * can result in fault, which will cause a deadlock when called with > * mmap_sem held > */ > - if (!is_exec && user_mode(regs)) > + if (is_write && user_mode(regs)) > store_update_sp = store_updates_sp(regs); > > if (user_mode(regs)) > -- > 2.12.0
On Wed, 2017-04-19 at 12:56:24 UTC, Christophe Leroy wrote: > Function store_updates_sp() checks whether the faulting > instruction is a store updating r1. Therefore we can limit its calls > to stores exceptions. > > This patch is an improvement of commit a7a9dcd882a67 ("powerpc: Avoid > taking a data miss on every userspace instruction miss") > > With the same microbenchmark app, run with 500 as argument, on an > MPC885 we get: > > Before this patch: 152000 DTLB misses > After this patch: 147000 DTLB misses > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Patches 1, 3, 4 and 5 applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/e8de85ca32f572f5dee00733022d8a cheers
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 3a7d580fdc59..67fefb59d40e 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -287,7 +287,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, * can result in fault, which will cause a deadlock when called with * mmap_sem held */ - if (!is_exec && user_mode(regs)) + if (is_write && user_mode(regs)) store_update_sp = store_updates_sp(regs); if (user_mode(regs))
Function store_updates_sp() checks whether the faulting instruction is a store updating r1. Therefore we can limit its calls to stores exceptions. This patch is an improvement of commit a7a9dcd882a67 ("powerpc: Avoid taking a data miss on every userspace instruction miss") With the same microbenchmark app, run with 500 as argument, on an MPC885 we get: Before this patch: 152000 DTLB misses After this patch: 147000 DTLB misses Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- arch/powerpc/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)