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Re: [Qemu-devel] [PATCHv2 2/9] cutils: add a function to find non-zero c
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCHv2 2/9] cutils: add a function to find non-zero content in a buffer |
Date: |
Tue, 19 Mar 2013 09:54:26 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
On 03/15/2013 09:50 AM, Peter Lieven wrote:
> Signed-off-by: Peter Lieven <address@hidden>
> ---
> include/qemu-common.h | 2 ++
> util/cutils.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 42 insertions(+)
>
>
> +#define BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR 8
Good.
> + assert(len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
> + * sizeof(VECTYPE)) == 0);
Good use of it.
> + assert(((uintptr_t) buf) % sizeof(VECTYPE) == 0);
> +
> + if (*((const long *) buf)) {
> + return 0;
> + }
> +
> + for (i = 0; i < len / sizeof(VECTYPE); i += 8) {
Magic number 8, instead of reusing BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR.
> + VECTYPE tmp0 = p[i+0] | p[i+1];
Indentation looks off, because you used TABs.
Spaces around binary operators (two instances of '+' per line).
> + VECTYPE tmp1 = p[i+2] | p[i+3];
> + VECTYPE tmp2 = p[i+4] | p[i+5];
> + VECTYPE tmp3 = p[i+6] | p[i+7];
> + VECTYPE tmp01 = tmp0 | tmp1;
> + VECTYPE tmp23 = tmp2 | tmp3;
> + if (!ALL_EQ(tmp01 | tmp23, zero)) {
> + break;
> + }
> + }
> + return i * sizeof(VECTYPE);
> +}
Algorithm looks correct, but worth a respin to fix the appearance.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- Re: [Qemu-devel] [PATCHv2 8/9] migration: do not search dirty pages in bulk stage, (continued)
[Qemu-devel] [PATCHv2 7/9] migration: do not sent zero pages in bulk stage, Peter Lieven, 2013/03/15
[Qemu-devel] [PATCHv2 5/9] migration: search for zero instead of dup pages, Peter Lieven, 2013/03/15
[Qemu-devel] [PATCHv2 1/9] move vector definitions to qemu-common.h, Peter Lieven, 2013/03/15