Subject: Re: [RFC] tcp: use order-3 pages in tcp_sendmsg()

From: Alexander Duyck <[email-masked]>
Date: Wed, 19 Sep 2012 12:04:36 -0700

On 09/19/2012 10:56 AM, David Miller wrote:
> From: Eric Dumazet <[email-masked]>
> Date: Wed, 19 Sep 2012 17:14:19 +0200
>
>> I did some tests and got no problem so far, even using splice() [ this
>> one was tricky because it only deals with order-0 pages at this moment ]
>>
>> NIC tested : ixgbe, igb, bnx2x, tg3, mellanox mlx4
>>
>> On loopback, performance of netperf goes from 31900 Mb/s to 38500 Mb/s,
>> thats a 20 % increase.
> That's really a lot more than I expected, nice.

When I get some time I will test this patch on a system with an iommu
enabled.  I suspect it will have a huge performance impact there since
now you would be looking at roughly 1/8th the total number of map/unmap
calls on a system with 4K pages.

Thanks,

Alex