Re: Buffer alignment

[Loic Dachary <loic@dachary.org>]

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On 11/12/2013 10:50, Andreas Joachim Peters wrote:
> Hi Loic, 
> if you pull the BPC extension this requires 128-bit aligned memory adresses, maybe to prepare for future extensions they should be even 512-bit aligned. I can add an assertion if I see unaligned addresses.
> 

Could you please remind me which branch of your repository I should look at ?

Cheers

> Cheers Andreas.
> 
> ________________________________________
> From: Loic Dachary [loic@dachary.org]
> Sent: 10 December 2013 09:32
> To: Andreas Joachim Peters
> Cc: Ceph Development
> Subject: Buffer alignment
> 
> Hi Andreas,
> 
> In Ceph, buffers can be aligned if required using buffer::create_page_aligned
> 
> https://github.com/ceph/ceph/blob/master/src/common/buffer.cc#L519
> https://github.com/ceph/ceph/blob/master/src/common/buffer.cc#L230
> 
> and although the Jerasure plugin has alignment requirements
> 
> https://github.com/ceph/ceph/blob/master/src/osd/ErasureCodePluginJerasure/ErasureCodeJerasure.cc#L79
> 
> it did not occur to me that aligning the buffers used to stored the encoded
> 
> https://github.com/ceph/ceph/blob/master/src/osd/ErasureCodePluginJerasure/ErasureCodeJerasure.cc#L87
> 
> result would be needed. For decoding the caller is responsible for allocating the buffers. For encoding it also is, except for the padding.
> 
> Do you think the API should recommend something regarding alignment ?
> 
> https://github.com/ceph/ceph/blob/master/src/osd/ErasureCodeInterface.h#L20
> 
> Cheers
> 
> --
> Loïc Dachary, Artisan Logiciel Libre
> 
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-- 
Loïc Dachary, Artisan Logiciel Libre


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