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Re: [Qemu-devel] [RFC][PATCH 4/9] buffer_is_zero: use vector optimizatio
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From: |
Eric Blake |
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Subject: |
Re: [Qemu-devel] [RFC][PATCH 4/9] buffer_is_zero: use vector optimizations if possible |
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Date: |
Tue, 12 Mar 2013 10:09:35 -0600 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130219 Thunderbird/17.0.3 |
On 03/12/2013 10:03 AM, Peter Lieven wrote:
>>> + if (((uintptr_t) buf) % sizeof(VECTYPE) == 0
>>> + && len % 8*sizeof(VECTYPE) == 0) {
>>
>> Space around binary operators. Use CHAR_BITS instead of a magic number
>> 8.
> the 8 is not BITS_PER_BYTE or CHAR_BITS its the number of
> vectors in one loop in buffer_find_nonzero_offset(). I will add
> a constant for this to make it clearer.
Indeed, now I see it - 8 is the unroll factor. Well, all the more
evidence that a named constant makes the code easier to read, compared
to me mis-interpreting the magic number.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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