Re: IP over Fibre Channel slower than GigaEthernet ?

[Zhiwen Zheng]

Could someone point me to resources about doing zero copy in kernel,
such as RDMA over IP, RDMA over FC , please?

2008/12/10 Zhiwen Zheng <zhiwen.zh@xxxxxxxxx>:
> Hi,
>
> To compare tcp transport speed of IP over FC to that of GigaEthernet,
> I have two machines connected directly with FC or GigaEther, and run
> ttcp to get the result.
>
> configuration of the machines:
> kernel version : 2.6.10
> platform : xscale iop80331 500MHz
> memory : 512MB DDR2
> FC controller : LSI FC949x (using driver mptlan.c)
> GigaEthernet controller : Intel 82546EB
>
>
> In the Ethernet case,  the transport speed is about 90MB/s,
> and cpu usage is about 90%.
>
> In the FC case, the transport speed is about 60MB/s,
> and cpu usage is also about 90%.
>
>  Could someone tell me why FC is slower than GigaEthernet?
> And is it possible to reduce the cpu usage through DMA or something else ?
>
> Thanks.
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/