Re: [PATCH for-3.11 7/7] IB/iser: Introduce fast memory registration model (FRWR)

[Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>]

On 07/23/13 16:21, Or Gerlitz wrote:
> Bart, iSER's FMR and FRWR code works under the assumption that an SG
> list is "4K aligned". For SGs which don't obey that assumption we're
> using bounce buffer.
>
> Note that the SG "page" size used by FMRs/FRWRs doesn't have to be 1:1
> with the OS page size, so in that respect && down the road, we will
> get rid of the bounce buffer thing with having another FMR/FRWR pool
> whose "page" size is 512B and will be used for SG which are not "4K
> aligned".

Sorry but I had overlooked the bounce buffer patch. Regarding page 
sizes: is an InfiniBand HCA required to support a page size of 512 bytes 
? To me it seems like the smallest page size supported by e.g. the 
ocrdma driver is 4KB. From ocrdma_query_device():

	attr->page_size_cap = 0xffff000;

Still regarding page sizes: shouldn't ib_alloc_fast_reg_page_list() and 
ib_alloc_fast_reg_mr() multiply the SG list length by PAGE_SIZE / 
SIZE_4K to compensate for page size differences on architectures where 
virtual memory pages are larger than 4KB ?

Bart.
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html