[POWERPC] cell: Unify spufs syscall path

At present, a built-in spufs will not use the spufs_calls callbacks, but
directly call sys_spu_create.  This saves us an indirect branch, but
means we have duplicated functions - one for CONFIG_SPU_FS=y and one for
=m.

This change unifies the spufs syscall path, and provides access to the
spufs_calls structure through a get/put pair.  At present, the only user
of the spufs_calls structure is spu_syscalls.c, but this will facilitate
adding the coredump calls later.

Everyone likes numbers, right?  Here's a before/after comparison with
CONFIG_SPU_FS=y, doing spu_create(); close(); 64k times.

Before:
	[jk@cell ~]$ time ./spu_create
	performing 65536 spu_create calls

	real    0m24.075s
	user    0m0.146s
	sys     0m23.925s

After:
	[jk@cell ~]$ time ./spu_create
	performing 65536 spu_create calls

	real    0m24.777s
	user    0m0.141s
	sys     0m24.631s

So, we're adding around 11us per syscall, at the benefit of having
only one syscall path.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 2bfdeb8ea8bd..3dbffebb3cef 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -200,6 +200,7 @@ extern struct tree_descr spufs_dir_contents[];
 extern struct tree_descr spufs_dir_nosched_contents[];
 
 /* system call implementation */
+extern struct spufs_calls spufs_calls;
 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *status);
 long spufs_create(struct nameidata *nd, unsigned int flags,
                         mode_t mode, struct file *filp);