On Tue, 8 Jul 2014, Matt Thomas wrote:
On Jul 7, 2014, at 11:35 PM, Emmanuel Dreyfus <manu%netbsd.org@localhost> wrote:ixg0: PCI Express Bus: Speed 2.5Gb/s Width x8 Is it 2.5 Gb/s maximum (in which case I hit that limit), or 2.5x8 = 20 Gb/s in which case I still have room for improvment.The latter.
2.5 x 8 Gt/s. Gigatransfers per second. Each packet has a payload size of 128 or 256 bytes, typically, on a very chatty bus, so you really want PCIe Gen 2 speeds of 5GT/s x 8 for an 82599 NIC in some cases. Another thing is to increase the frame size. Small packet performance won't ever hit line rate (64B packet data) but I think you have other problems before you even get close to that. -- Hisashi T Fujinaka - htodd%twofifty.com@localhost BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte