Pavel Machek wrote: > Hi! > > I've found that gbit vs. 100mbit power consumption difference is about > 1W -- pretty significant. (Maybe powertop should include it in the > tips section? :). > > Energy Star people insist that machines should switch down to 100mbit > when network is idle, and I guess that makes a lot of sense -- you > save 1W locally and 1W on the router. > > Question is, how to implement it correctly? Daemon that would watch > data rates and switch speeds using mii-tool would be simple, but is > that enough?
you most certainly want to do this in userspace I think. One of the biggest problems is that link negotiation can take a significant amount of time, well over several seconds (1 to 3 seconds typical) with gigabit, and having your ethernet connection go offline for 3 seconds may not be the desired effect for when you want to get more bandwidth in the first place. However, when a laptop is in battery mode, switching down from gigabit to 100mbit makes a lot more sense, so this is something I would recommend. This can be as easy as changing the advertisement mask of the interface and renegotiating the link. Userspace could handle that very easily. Auke - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/