Messages in this thread | | | Date | Thu, 07 Jan 2010 00:32:05 -0500 | From | Michael Breuer <> | Subject | Re: [PATCH] af_packet: Don't use skb after dev_queue_xmit() |
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On 1/6/2010 11:53 PM, Stephen Hemminger wrote: > On Wed, 06 Jan 2010 23:00:34 -0500 > Michael Breuer<mbreuer@majjas.com> wrote: > > >> Changing MTU to 9000, everything basically breaks - Can't use X11 (local >> or remote - get X11 screen after gdm login locally, but then goes back >> to greeter; remote gets no greeter); ssh sessions hang; etc. This time I >> was able to reset the MTU back to 1500 without a reboot - but I did have >> to ifconfig eth0 down and then up. Looking at the sk98lin code, it looks >> to me like they do a bit more work with existing buffers before >> completing the MTU switch. Note that even doing this, X11 did not work >> (it did with the old mtu change code). Tried changing to mtu 4500 - same >> effect as 9000... but when I switched back to 1500, ksoftirqd started >> spinning using 100% of one core. >> > The problem is that patch was enabling scatter-gather and checksum offload > that won't work on EC_U hardware with 9K MTU. At least, it never worked > for me when I tested it. So because of that it really doesn't change anything > for the better on that chip version. > > What version chip is on that motherboard? Mine is: > Yukon-2 EC Ultra chip revision 3 > which corresponds to B0 step. > > Another possibility is the PHY register which controls number of ticks > of buffering. The default is zero, which gives the most buffering (good), > but the firmware could be reprogramming it (bad). In general, the driver > doesn't fiddle with bits that are already set correctly, because sometimes > vendors need to tweak PCI timing in firmware/BIOS. It seems the firmware on this > chip is just a bunch of register setups done on power on. > Also - I'm seeing a huge number of dropped packets (RX) 200-300/second. Probably why this is so slow.
Current ifconfig: eth0 Link encap:Ethernet HWaddr 00:26:18:00:1C:3B inet addr:10.0.0.1 Bcast:10.0.0.255 Mask:255.255.255.0 inet6 addr: fe80::226:18ff:fe00:1c3b/64 Scope:Link UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 RX packets:26647536 errors:0 dropped:517884 overruns:0 frame:0 TX packets:12112780 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:38960063319 (36.2 GiB) TX bytes:1889879762 (1.7 GiB) Interrupt:18
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