Hi all, I've got some general questions around the expected behaviour of the 82576 igb net device. (On a dual quad-core Nehalem box, if it matters.)
As a caveat, the box is running Centos 5.3 with their 2.6.18 kernel. It's using the 1.3.16-k2 igb driver though, which looks to be the one from mainline linux. The igb driver is being loaded with no parameters specified. At driver init time, it's selecting 1 tx queue and 4 rx queues per device. My first question is whether the number of queues makes sense. I couldn't figure out how this would happen since the rules for selecting the number of queues seems to be the same for rx and tx. Also, it's not clear to me why it's limiting itself to 4 rx queues when I have 8 physical cores (and 16 virtual ones with hyperthreading enabled). My second question is around how the rx queues are mapped to interrupts. According to /proc/interrupts there appears to be a 1:1 mapping between queues and interrupts. However, I've set up at test with a given amount of traffic coming in to the device (from 4 different IP addresses and 4 ports). Under this scenario, "ethtool -S" shows the number of packets increasing for only rx queue 0, but I see the interrupt count going up for two interrupts. My final question is around smp affinity for the rx and tx queue interrupts. Do I need to affine the interrupt for each rx queue to a single core to guarantee proper packet ordering, or can they be handled on arbitrary cores? Should the tx queue be affined to a particular core or left to be handled by all cores? Thanks, Chris ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel
