Changing default module options

[Zhu Yi]

On Mon, 2010-03-22 at 22:13 +0800, Stanislaw Gruszka wrote:
> 
> Changing default options in upstream kernel is problematic. Since
> 2.6.33 we have different memory allocations to avoid failures due to
> buddy allocator fragmentation. It is optimized for normal usage case,
> but with swcrypto when and skb's have to be linearized memory usage by
> driver increase about 2 times. 

Have you benchmarked about this change? Before paged Rx skb is used, we
have to allocate (8K + sizeof(struct skb_shared_info)) linear skb, which
is an order-2 allocation. Now with paged skb, first we do an order-1
allocation to hold the packet from device, then skb_linearize (if
swcrypto is used) the skb. Note, in most of the time, the skb->len will
be far less than 8K (unless 11n aggregation is used). So normally
skb_linearize only does an order-1 (or even order-0) allocation in most.
So in the swcrypto case, the paged Rx patch changes the memory
allocation from one order-2 into two separated order-1 allocations. It
should still be an improvement. No?

Thanks,
-yi