Arjan van de Ven wrote: > Most offload features (TSO etc) end up helping (a little). Anything that > makes the system more efficient will help; it's the "if you have less > work to do > you consume less power" concept. > Exception tends to be TOE (total offloading), since TOE tends to be > implemented > by just another CPU, one on the card. This tends to be a loss in terms > of power, > because you now have 2 cpus slurping power, having just one tends to be > more > optimal. > > As for powertop suggesting this: I'm actually surprised these features > arent > on by default already. They should be.... > If you have a specific one in mind, can you give some examples? It's easier > to discuss such things on a specific case basis
I have three machines with different ethernet chips in them. None of them come with all of the offloading features that they support enabled on boot. For example, the via-velocity in one machine supports only one offload (which I now know is not hardware-assisted): [EMAIL PROTECTED]:~# ethtool -k eth0 Offload parameters for eth0: Cannot get device rx csum settings: Operation not supported Cannot get device tx csum settings: Operation not supported Cannot get device scatter-gather settings: Operation not supported Cannot get device tcp segmentation offload settings: Operation not supported Cannot get device udp large send offload settings: Operation not supported rx-checksumming: off tx-checksumming: off scatter-gather: off tcp segmentation offload: off udp fragmentation offload: off generic segmentation offload: off [EMAIL PROTECTED]:~# lspci -vv | grep Ethernet 00:0e.0 Ethernet controller: VIA Technologies, Inc. VT6120/VT6121/VT6122 Gigabit Ethernet Adapter (rev 11) Same with the natsemi chip in another machine: [EMAIL PROTECTED]:~# ethtool -k eth0 Offload parameters for eth0: Cannot get device rx csum settings: Operation not supported Cannot get device tx csum settings: Operation not supported Cannot get device scatter-gather settings: Operation not supported Cannot get device tcp segmentation offload settings: Operation not supported Cannot get device udp large send offload settings: Operation not supported rx-checksumming: off tx-checksumming: off scatter-gather: off tcp segmentation offload: off udp fragmentation offload: off generic segmentation offload: off [EMAIL PROTECTED]:~# lspci -vv | grep Ethernet 00:06.0 Ethernet controller: National Semiconductor Corporation DP83815 (MacPhyter) Ethernet Controller I cannot reboot the third machine (which has an r8169 device) at the moment, but whereas it does support several hardware-assisted offload features I seem to remember that only checksumming is enabled at boot (but I can't remember whether it's rx or tx, but definitely not both). I have since enabled all of the other features to produce the following: [EMAIL PROTECTED]:~# ethtool -k eth0 Offload parameters for eth0: Cannot get device udp large send offload settings: Operation not supported rx-checksumming: on tx-checksumming: on scatter-gather: on tcp segmentation offload: on udp fragmentation offload: off generic segmentation offload: on [EMAIL PROTECTED]:~# lspci -vv | grep Ethernet 00:09.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8110SC/8169SC Gigabit Ethernet (rev 10) All of the above machines run Ubuntu 7.10 with a 2.6.22-based kernel. Thanks, Jan _______________________________________________ Power mailing list [email protected] http://www.bughost.org/mailman/listinfo/power
