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authorDavid S. Miller <davem@davemloft.net>2008-10-29 21:25:00 -0700
committerDavid S. Miller <davem@davemloft.net>2008-12-04 09:16:46 -0800
commit64f2dde3f743c8a1ad8c0a1aa74166c1034afd92 (patch)
tree5033069de9784f6c2a6f545e5dfafa97a2b430d8 /arch/sparc
parentc9bb6003dd096ad190e1594a7d835ae1c39fae8f (diff)
sparc64: Run the kernel always in the TSO memory model.
The fact of the matter is, all UltraSPARC-III and later chips only implement TSO. They don't implement PSO and RMO memory models at all. Only the Ultra-I and Ultra-II family chips implement RMO and they are only helped marginally by using this setting when executing kernel code. The big plus to doing this is that we can eliminate all of the non-Sync memory barriers in the kernel except for the ones used in the optimized memcpy/memset code (these use block load and store operations which have their own memory ordering rules). Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc')
-rw-r--r--arch/sparc/include/asm/spinlock_64.h17
1 files changed, 6 insertions, 11 deletions
diff --git a/arch/sparc/include/asm/spinlock_64.h b/arch/sparc/include/asm/spinlock_64.h
index 120cfe4577c..fbac9d00744 100644
--- a/arch/sparc/include/asm/spinlock_64.h
+++ b/arch/sparc/include/asm/spinlock_64.h
@@ -13,17 +13,12 @@
* and rebuild your kernel.
*/
-/* All of these locking primitives are expected to work properly
- * even in an RMO memory model, which currently is what the kernel
- * runs in.
- *
- * There is another issue. Because we play games to save cycles
- * in the non-contention case, we need to be extra careful about
- * branch targets into the "spinning" code. They live in their
- * own section, but the newer V9 branches have a shorter range
- * than the traditional 32-bit sparc branch variants. The rule
- * is that the branches that go into and out of the spinner sections
- * must be pre-V9 branches.
+/* Because we play games to save cycles in the non-contention case, we
+ * need to be extra careful about branch targets into the "spinning"
+ * code. They live in their own section, but the newer V9 branches
+ * have a shorter range than the traditional 32-bit sparc branch
+ * variants. The rule is that the branches that go into and out of
+ * the spinner sections must be pre-V9 branches.
*/
#define __raw_spin_is_locked(lp) ((lp)->lock != 0)