svn commit: r271946 - in head/sys: dev/oce dev/vmware/vmxnet3 dev/xen/netfront kern net netinet ofed/drivers/net/mlx4 sys

[Roger Pau Monné]

El 22/09/14 a les 10.27, Hans Petter Selasky ha escrit:
> Author: hselasky
> Date: Mon Sep 22 08:27:27 2014
> New Revision: 271946
> URL: http://svnweb.freebsd.org/changeset/base/271946
> 
> Log:
>   Improve transmit sending offload, TSO, algorithm in general.
>   
>   The current TSO limitation feature only takes the total number of
>   bytes in an mbuf chain into account and does not limit by the number
>   of mbufs in a chain. Some kinds of hardware is limited by two
>   factors. One is the fragment length and the second is the fragment
>   count. Both of these limits need to be taken into account when doing
>   TSO. Else some kinds of hardware might have to drop completely valid
>   mbuf chains because they cannot loaded into the given hardware's DMA
>   engine. The new way of doing TSO limitation has been made backwards
>   compatible as input from other FreeBSD developers and will use
>   defaults for values not set.
>   
>   Reviewed by:	adrian, rmacklem
>   Sponsored by:	Mellanox Technologies

This commit makes xen-netfront tx performance drop from ~5Gbits/sec
(with debug options enabled) to 446 Mbits/sec. I'm currently looking,
but if anyone has ideas they are welcome.

Roger.