Thread (30 messages) 30 messages, 3 authors, 2016-02-07

Re: [PATCH v5 21/23] powerpc: Simplify test in __dma_sync()

flat view

From: Denis Kirjanov <hidden>
Date: 2016-02-04 11:56:04
Also in: lkml

On 2/4/16, Christophe Leroy [off-list ref] wrote:
quoted hunk ↗ jump to hunk
This simplification helps the compiler. We now have only one test
instead of two, so it reduces the number of branches.

Signed-off-by: Christophe Leroy <redacted>
---
v2: new
v3: no change
v4: no change
v5: no change

 arch/powerpc/mm/dma-noncoherent.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/dma-noncoherent.c
b/arch/powerpc/mm/dma-noncoherent.c
index 169aba4..2dc74e5 100644
--- a/arch/powerpc/mm/dma-noncoherent.c
+++ b/arch/powerpc/mm/dma-noncoherent.c
@@ -327,7 +327,7 @@ void __dma_sync(void *vaddr, size_t size, int direction)
 		 * invalidate only when cache-line aligned otherwise there is
 		 * the potential for discarding uncommitted data from the cache
 		 */
-		if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1)))
+		if ((start | end) & (L1_CACHE_BYTES - 1))
 			flush_dcache_range(start, end);
 		else
 			invalidate_dcache_range(start, end);
The previous version of address cache-line aligned check reads perfectly fine.
What's the benefit of this micro optimization?
--
2.1.0

_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help