Thomas, John,
thanks for your notes.
Enclosed the contents of our chats,
On 13/10/2015 18:36, Mcnamara, John wrote:
> * PMD lite
>
> - Do we need a lighter PMD model? Perhaps based on the Mellanox
> model.
> - Vincent suggested be could remove 90% of the code. I'll leave
> Vincent explain this one.
benefits of 100% userland drivers:
- no dependency on getting kernel patch upstreams first
- it is possible to run on a latest HW even when the Linux host (or
host OS) does not support the new NIC/boards supported by the DPDK
drawbacks of 100% userland drivers:
- redundancy of source code (duplication into the kernel and userland)
=> more maintenance
- DPDK PMDs are in fact outdated while kernel drivers are supporting
latest HW (port management - optics - , latest HW revisions, managing
firmware updates) more frequently
- do not run when not root applications
- cannot reuse port management tools from the kernels (ethtool, etc.)
ixgbe pmd
=========
100% lines of userland
must be run as root
~ 40K lines
~ kernel overlaps with
http://dpdk.org/browse/dpdk/tree/drivers/net/ixgbe/base
~ mostly only
http://dpdk.org/browse/dpdk/tree/drivers/net/ixgbe/ixgbe_rxtx[_vec].c is
needed, other files are not needed (6k lines of code)
mlx4 pmd
========
10% lines userland, then using kernel's ones
could be run as a non root process
~ 5.2K lines of code
~ the rxtx.c file is http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4/
BUT using infiniband :( => should be cleand up to use bare minimum like,
+ /* Allocate protection domain. */
http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4/mlx4.c#n4828
+ Register memory regions -> ibv_reg_mr()
http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4/mlx4.c#n792
Best regards,
Vincent
