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[Qemu-devel] [PATCHv5 04/10] buffer_is_zero: use vector optimizations if
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv5 04/10] buffer_is_zero: use vector optimizations if possible |
Date: |
Tue, 26 Mar 2013 10:58:33 +0100 |
performance gain on SSE2 is approx. 20-25%. altivec
is not tested. performance for unsigned long arithmetic
is unchanged.
Signed-off-by: Peter Lieven <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Orit Wasserman <address@hidden>
---
util/cutils.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/util/cutils.c b/util/cutils.c
index 0314a18..daf032a 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -215,6 +215,11 @@ 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);
--
1.7.9.5
- [Qemu-devel] [PATCHv5 00/10] buffer_is_zero / migration optimizations, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 04/10] buffer_is_zero: use vector optimizations if possible,
Peter Lieven <=
- [Qemu-devel] [PATCHv5 05/10] bitops: unroll while loop in find_next_bit(), Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 08/10] migration: do not sent zero pages in bulk stage, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 09/10] migration: do not search dirty pages in bulk stage, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 07/10] migration: add an indicator for bulk state of ram migration, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 06/10] migration: search for zero instead of dup pages, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 10/10] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 01/10] move vector definitions to qemu-common.h, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 02/10] add a zero splat vector to qemu-common.h, Peter Lieven, 2013/03/26