[rds-devel] dma_sync [was: Has anyone tried RDS on IA64 Linux?]

[Or Gerlitz]

Olaf Kirch wrote:
> RDS headers are in DMA consistent memory, so there's no explicit
> dma_sync required. Correct?
not that I understand why DMA consistent memory is used for data 
buffers, but since this is the case, I think you are right on this 
observation.

> Given that logic, we would really need to sync explicitly when
> we receive a RDS packet that does not use the last fragment of the
> mapped page, correct? Proposed patch below...
sounds correct, see one comment on your patch below

Or.


> net/rds/ib_recv.c |    4 ++++
>  1 file changed, 4 insertions(+)
>
> Index: ofa_kernel-1.3/net/rds/ib_recv.c
> ===================================================================
> --- ofa_kernel-1.3.orig/net/rds/ib_recv.c
> +++ ofa_kernel-1.3/net/rds/ib_recv.c
> @@ -75,6 +75,10 @@ static void rds_ib_recv_unmap_page(struc
>                 ib_dma_unmap_page(ic->i_cm_id->device,
>                                recv->r_sge[0].addr - recv->r_frag->f_offset,
>                                PAGE_SIZE, DMA_FROM_DEVICE);
> +       else
> +               ib_dma_sync_single_for_device(ic->i_cm_id->device,
> +                               recv->r_sge[0].addr - recv->r_frag->f_offset,
> +                               PAGE_SIZE, DMA_FROM_DEVICE);
>   
isn't RDS_FRAG_SIZE needed here and not PAGE_SIZE?
>         recv->r_sge[0].addr = 0;
>  }