On Fri, 2009-08-28 at 21:03 +0200, Rafael J. Wysocki wrote: > On Friday 28 August 2009, Leisner, Martin wrote: > > While doing some current probe measurements (i.e. to measure the effects > > of NAP and frequency scaling with a freescale processor) I noticed some > > very > > significant differents if we ran on 100Mbit of 1000Mbit ethernet. > > > > The hardware guys like at their data sheets and agreed. > > > > Does anyone "drop ethernet speed" to save power? > > (when a system is idle, is isn't necessary to run 1G ethernet). > > I don't know, really. This is a netdev question IMO (CC added). Doing this through the existing autonegotiation mechanism is a bad idea, because it requires bringing the link down, possibly for a few seconds. There is a standard on the way (802.3az, aka Energy-Efficient Ethernet or EEE) which will allow for speed renegotiation without dropping the link. > > When a system has WOL capability, what speed does it run at when the > > system is sleeping? > > That's a very good question. I bet that depends on the NIC in question, at > least I'm not sure if any spec regulates it. I'm not aware of a spec, but generally a 1G or 10G multi-speed PHY will not advertise speeds higher than 100 Mbit/s when sleeping. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
