On Sun, 2013-10-20 at 00:32 +0200, Petar Bogdanovic wrote: > On Sat, Oct 19, 2013 at 10:34:18PM +0200, Petar Bogdanovic wrote: > > > > I managed to build and run the most recent e1000e kernel module (and > > experimented with its module options) but it didn't make any difference. > > I forgot the crucial part (the testing above happened a while ago): > > "Link Speed was downgraded by SmartSpeed" > > Based on what I've read, SmartSpeed "downshifts" when problems arise > (due to faulty cables etc.). However, when I connect the same cable > to a MacBook or a Thinkpad, GigE works fine.
SmartSpeed is an algorithm that serves at link auto-negotiation where there is none. It tries to link at the highest speed, and if it can't, will downshift and try again. The purpose is to work around faulty equipment so you at least have link, instead of no link at all. The quick history behind it is we implemented it on 10GbE first, where no spec existed for auto-negotiation for 10GbE-1GbE with fiber. We had optics modules that could do either 10 or 1 GbE, but no link-layer mechanism to autoneg the speed. So we implemented it in software and got it working, and called it SmartSpeed. This is a backport to other parts that can benefit from the same methods. Cheers, -PJ ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135031&iu=/4140/ostg.clktrk _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
