From: Peter Lieven <pl@dlhnet.de>
To: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Orit Wasserman <owasserm@redhat.com>,
Stefan Hajnoczi <stefanha@gmail.com>
Subject: [Qemu-devel] [RFC][PATCH 4/9] buffer_is_zero: use vector optimizations if possible
Date: Tue, 12 Mar 2013 16:50:31 +0100 [thread overview]
Message-ID: <513F4EC7.6010109@dlhnet.de> (raw)
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 a09d8e8..23f0cd6 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -186,6 +186,11 @@ bool buffer_is_zero(const void *buf, size_t len)
* latency.
*/
+ if (((uintptr_t) buf) % sizeof(VECTYPE) == 0
+ && len % 8*sizeof(VECTYPE) == 0) {
+ return buffer_find_nonzero_offset(buf, len)==len;
+ }
+
size_t i;
long d0, d1, d2, d3;
const long * const data = buf;
--
1.7.9.5
next reply other threads:[~2013-03-12 15:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-12 15:50 Peter Lieven [this message]
2013-03-12 16:01 ` [Qemu-devel] [RFC][PATCH 4/9] buffer_is_zero: use vector optimizations if possible Eric Blake
2013-03-12 16:03 ` Peter Lieven
2013-03-12 16:09 ` Eric Blake
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