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.
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