Re: [E1000-devel] [PATCH 01/21] net: slight optimization of addr compare for some modules

Greg Rose
2013-12-23T18:09:15Z

On Mon, 23 Dec 2013 09:20:37 -0800
Alexander Duyck <alexander.h.duyck@intel.com> wrote:

> On 12/22/2013 09:09 PM, Ding Tianhong wrote:
> > Use the recently added and possibly more efficient
> > ether_addr_equal_unaligned to instead of memcmp.
> >
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Cc: netdev@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: e1000-devel@lists.sourceforge.net
> > Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
> > ---
> > drivers/net/bonding/bond_3ad.c | 2 +-
> > drivers/net/ethernet/3com/3c509.c | 3 +--
> > drivers/net/ethernet/broadcom/bnx2x/bnx2x_sp.c | 10
> > ++++------ drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c |
> > 2 +- drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c | 2 +-
> > drivers/net/ethernet/chelsio/cxgb3/cxgb3_offload.c | 2 +-
> > drivers/net/ethernet/chelsio/cxgb3/l2t.c | 2 +-
> > drivers/net/ethernet/cisco/enic/enic_pp.c | 2 +-
> > drivers/net/ethernet/emulex/benet/be_main.c | 2 +-
> > drivers/net/ethernet/intel/igbvf/netdev.c | 2 +-
> > drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c | 3 +--
> > drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 4 ++--
> > drivers/net/ethernet/mellanox/mlx4/resource_tracker.c | 2 +-
> > drivers/net/ethernet/micrel/ksz884x.c | 9
> > ++++----- drivers/net/ethernet/neterion/vxge/vxge-main.c |
> > 2 +- drivers/net/ethernet/packetengines/yellowfin.c | 8
> > ++------ drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c | 2
> > +- drivers/net/ethernet/qlogic/qlcnic/qlcnic_hw.c | 4 ++--
> > drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c | 4 ++--
> > drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c | 4 ++--
> > drivers/net/ethernet/renesas/sh_eth.c | 2 +-
> > drivers/net/ethernet/seeq/sgiseeq.c | 2 +-
> > drivers/net/ethernet/sun/sunvnet.c | 2 +-
> > drivers/net/ethernet/ti/cpsw_ale.c | 2 +-
> > drivers/net/fddi/skfp/fplustm.c | 3 ++-
> > drivers/net/plip/plip.c | 2 +-
> > net/caif/cfrfml.c | 2 +-
> > 27 files changed, 39 insertions(+), 47 deletions(-)
>
> What is it you are trying to optimize for, size or speed? Most of
> these calls are in slow path. Replacing the memcmp with an inline
> operation may provide little to no gain in terms of speed and in many
> cases as you might actually be increasing the resultant driver size.
>
> Also I would recommend reviewing the addresses you are comparing. It
> is likely that you could use ether_addr_equal or compare_ether_addr
> in many cases as I suspect a number of spots are using 16b aligned
> MAC addresses for both operands.

User ether_addr_equal. compare_ether_addr was recently removed from
the upstream kernel - as I discovered to my chagrin late one
recent Friday evening while trying to get a build done.

- Greg

>
> Thanks,
>
> Alex
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