[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v3 6/9] cutils: Add generic prefetch
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH v3 6/9] cutils: Add generic prefetch |
Date: |
Mon, 29 Aug 2016 11:46:17 -0700 |
There's no real knowledge of the cacheline size,
just prefetching one loop ahead.
Signed-off-by: Richard Henderson <address@hidden>
---
util/bufferiszero.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/util/bufferiszero.c b/util/bufferiszero.c
index c356415..2c5801b 100644
--- a/util/bufferiszero.c
+++ b/util/bufferiszero.c
@@ -38,6 +38,8 @@ static bool NAME(const void *buf, size_t len)
\
do { \
const VECTYPE *p = buf; \
VECTYPE t; \
+ __builtin_prefetch(buf + SIZE); \
+ barrier(); \
if (SIZE == sizeof(VECTYPE) * 4) { \
t = (p[0] | p[1]) | (p[2] | p[3]); \
} else if (SIZE == sizeof(VECTYPE) * 8) { \
@@ -239,6 +241,9 @@ bool buffer_is_zero(const void *buf, size_t len)
return true;
}
+ /* Fetch the beginning of the buffer while we select the accelerator. */
+ __builtin_prefetch(buf);
+
/* Use an optimized zero check if possible. Note that this also
includes a check for an unrolled loop over longs, as well as
the unsized, unaligned fallback to buffer_zero_base. */
--
2.7.4
- [Qemu-devel] [PATCH v3 0/9] Improve buffer_is_zero, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 3/9] cutils: Export only buffer_is_zero, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 1/9] cutils: Move buffer_is_zero and subroutines to a new file, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 4/9] cutils: Rearrange buffer_is_zero acceleration, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 9/9] cutils: Remove ppc buffer zero checking, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 8/9] cutils: Remove aarch64 buffer zero checking, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 6/9] cutils: Add generic prefetch,
Richard Henderson <=
- [Qemu-devel] [PATCH v3 5/9] cutils: Add test for buffer_is_zero, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 7/9] cutils: Rewrite x86 buffer zero checking, Richard Henderson, 2016/08/29
- Re: [Qemu-devel] [PATCH v3 0/9] Improve buffer_is_zero, Paolo Bonzini, 2016/08/30