1. 30 4月, 2007 1 次提交
    • S
      ieee1394: sbp2: remove unnecessary alignments of struct members · f412bf44
      Stefan Richter 提交于
      The members "dma_addr_t command_orb_dma" and "dma_addr_t sge_dma" of
      sbp2.h::sbp2_command_info do not have to be aligned themselves --- only
      the memory which they point to has to be.
      
      The member "struct sbp2_command_orb command_orb" has to be aligned on
      4 bytes boundary which is guaranteed because it contains u32 members.
      
      The member "struct sbp2_unrestricted_page_table scatter_gather_element",
      i.e. the SBP-2 s/g table, has to be aligned on 8 bytes boundary
      according to the SBP-2 spec.  This is not a requirement for FireWire
      controllers but could be expected by SBP-2 targets.
      
      I see no need to align the members command_orb and
      scatter_gather_element on CPU cacheline boundaries.  It could have
      performance benefits, but on the other hand sbp2 has a somewhat wasteful
      allocation scheme which should be optimized first before further tweaks
      like cacheline alignments.  (E.g. don't always allocate SG_ALL s/g table
      elements.)
      
      Note, before as well as after the patch, the code relies on the
      assumption that memory alignment in the virtual address space is
      preserved in the physical address space after DMA mapping.
      Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>
      f412bf44
  2. 28 4月, 2007 39 次提交