Patchwork [PATCHv3,3/9] buffer_is_zero: use vector optimizations if possible

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Submitter Peter Lieven
Date March 21, 2013, 3:57 p.m.
Message ID <1363881457-14814-4-git-send-email-pl@kamp.de>
Download mbox | patch
Permalink /patch/229747/
State New
Headers show

Comments

Peter Lieven - March 21, 2013, 3:57 p.m.
performance gain on SSE2 is approx. 20-25%. altivec
is not tested. performance for unsigned long arithmetic
is unchanged.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 util/cutils.c |    5 +++++
 1 file changed, 5 insertions(+)
Eric Blake - March 21, 2013, 6:16 p.m.
On 03/21/2013 09:57 AM, Peter Lieven wrote:
> performance gain on SSE2 is approx. 20-25%. altivec
> is not tested. performance for unsigned long arithmetic
> is unchanged.
> 
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  util/cutils.c |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/util/cutils.c b/util/cutils.c
> index 6d079ac..52205a2 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -210,6 +210,11 @@ bool buffer_is_zero(const void *buf, size_t len)
>      long d0, d1, d2, d3;
>      const long * const data = buf;
>  
> +    /* use vector optimized zero check if possible */
> +    if (can_use_buffer_find_nonzero_offset(buf,len)) {

Space after comma.

> +        return buffer_find_nonzero_offset(buf, len)==len;

And still missing spaces around the '==', even though I pointed it out
in v2.  Run your series through checkpatch.pl.

As whitespace cleanups are trivial, you can send v4 with:

Reviewed-by: Eric Blake <eblake@redhat.com>

Patch

diff --git a/util/cutils.c b/util/cutils.c
index 6d079ac..52205a2 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -210,6 +210,11 @@  bool buffer_is_zero(const void *buf, size_t len)
     long d0, d1, d2, d3;
     const long * const data = buf;
 
+    /* use vector optimized zero check if possible */
+    if (can_use_buffer_find_nonzero_offset(buf,len)) {
+        return buffer_find_nonzero_offset(buf, len)==len;
+    }
+
     assert(len % (4 * sizeof(long)) == 0);
     len /= sizeof(long);