On Sun, Jul 08, 2007 at 03:29:35PM -0700, Andrew Morton wrote: > > This problem does NOT seem to affect my Tsunami/Shark (EV68AL) box running > > the > > same kernel version on the same LAN. Not sure if it's CPU generation > > related > > (EV5 vs EV6), or if it's the NIC (via_rhine on the EV5 vs e100 on the EV6).
It is the NIC, I suppose. > I don't think there's necessarily a bug here: that's just the kernel > telling us that there are unaligned accesses which got successfully > fixed up, so we're being perhaps a bit inefficient. Yes? Sort of. It's not exactly a bug, just an old and well known problem with ethernet controllers that can do DMA only at 32-bit boundaries, so the IP headers are not properly aligned. A workaround is to disable "rx_copybreak" feature, either by passing "rx_copybreak=1536" to the driver, or add #ifdef to via_rhine.c, like tulip, starfire and many other drivers have: /* * Set the copy breakpoint for the copy-only-tiny-frames scheme. * Setting to > 1518 effectively disables this feature. * * NOTE: * The ia64 doesn't allow for unaligned loads even of integers being * misaligned on a 2 byte boundary. Thus always force copying of * packets as the starfire doesn't allow for misaligned DMAs ;-( * 23/10/2000 - Jes * * The Alpha and the Sparc don't like unaligned loads, either. On Sparc64, * at least, having unaligned frames leads to a rather serious performance * penalty. -Ion */ #if defined(__ia64__) || defined(__alpha__) || defined(__sparc__) static int rx_copybreak = PKT_BUF_SZ; #else static int rx_copybreak /* = 0 */; #endif Ivan. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
