I'm using a patched e1000e driver for control of a realtime process. Basically the code that's responsible for setting up the link on various e1000 derivatives is simply kept and e1000_xmit_frame / e1000_intr_msi are called directly. The e1000e (82574) family of cards has worked fine but I found that the more recent i217 does not do so well in this area. Whereas a 82574 starts transmitting on the wire after about 6 us, the i217 only does so after 20 (on an idle system), which ruins the realtime process.
While looking into this issue, I noticed that the default RXDCTL setting isn't touched by e1000e netdev/ich8lan and stays at 0x00010000, leading to RX descriptors being written back as soon as one cache line is filled (or one of the RDTR / RADV timers expires). Is this intentional ? Also, the default TXDCTL the i217 ends up with is 0x0141001f. Bit 22 is reserved per the Intel docs but is set nevertheless in ich8lan. What does it do ? Additionally, HTHRESH is zero whereas the docs mandate a nonzero value if PTHRESH is nonzero (is 0x1f now). And, of course, would anyone now why the i217 takes so long to fetch its descriptors and corresponding packet ? I apologize if this is too off-topic, but if anyone out there has practical knowledge of these chips, he or she is probably on this list. Thanks, Jeroen. . ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available. Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ 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
