[ofa-general] Re: [PATCH] IB/ipoib: IPOIB CM rx use higher order fragments

[Eli Cohen]

On Tue, 2007-10-23 at 11:35 -0700, Roland Dreier wrote:
> > In order to reduce the overhead of iterating the fragments of an
>  > SKB in the receive flow, we use fragments of higher order and thus
>  > reduce the number of iterations. This patch seams to improve receive
>  > throughput of small UDP messages.
> 
> I don't think we want to do this -- it may be good for benchmarks but
> it will hurt reliability, since systems often have highly fragmented
> memory so higher-order atomic allocations will fail.
> 
>  - R.

Other drivers do similar allocations. For example, e1000 when working
with jumbo frames does such large allocations. Also I did not notice
allocation failures though my system was pretty much active but I can
monitor for such possible failures.

e1000_main.c line 3549:

else if (max_frame <= E1000_RXBUFFER_16384)
		adapter->rx_buffer_len = E1000_RXBUFFER_16384;