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Re: [Qemu-devel] [PATCHv4 3/9] buffer_is_zero: use vector optimizations
From: |
Orit Wasserman |
Subject: |
Re: [Qemu-devel] [PATCHv4 3/9] buffer_is_zero: use vector optimizations if possible |
Date: |
Mon, 25 Mar 2013 10:53:45 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 |
On 03/22/2013 02:46 PM, 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 <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> ---
> util/cutils.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/util/cutils.c b/util/cutils.c
> index 41c627e..0f43c22 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -205,6 +205,11 @@ 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);
>
>
Reviewed-by: Orit Wasserman <address@hidden>
- [Qemu-devel] [PATCHv4 0/9] buffer_is_zero / migration optimizations, Peter Lieven, 2013/03/22
- [Qemu-devel] [PATCHv4 5/9] migration: search for zero instead of dup pages, Peter Lieven, 2013/03/22
- [Qemu-devel] [PATCHv4 3/9] buffer_is_zero: use vector optimizations if possible, Peter Lieven, 2013/03/22
- Re: [Qemu-devel] [PATCHv4 3/9] buffer_is_zero: use vector optimizations if possible,
Orit Wasserman <=
- [Qemu-devel] [PATCHv4 8/9] migration: do not search dirty pages in bulk stage, Peter Lieven, 2013/03/22
- [Qemu-devel] [PATCHv4 1/9] move vector definitions to qemu-common.h, Peter Lieven, 2013/03/22
- [Qemu-devel] [PATCHv4 9/9] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/22
- [Qemu-devel] [PATCHv4 4/9] bitops: use vector algorithm to optimize find_next_bit(), Peter Lieven, 2013/03/22
- [Qemu-devel] [PATCHv4 6/9] migration: add an indicator for bulk state of ram migration, Peter Lieven, 2013/03/22