Am Mittwoch 17 November 2010 schrieb RA-Jay Hung: > > > When inserting the l2pad we're moving the header and thus reduce headroom. > > > This patch modifies the bahavior during l2pad removal to not move the header > > > back into its old position but instead moves the payload. Thus the skb keeps > > > the reduced headroom. If this skb gets requeued into rt2x00 (which can happen > > > when the frame wasn't acked and the according STA is known to e in powersave > > > mode) the header and payload get aligned again further reducing headroom which > > > results in a too small headroom for the TXWI and thus a skb_under_panic. > > > > Hmm, John merged that patch already. However, I would prefer if it would get > > reverted due to the occasional panics in AP mode. > > > > Jay, I didn't notice any performance degradation on MIPS, on which architecture > > did you test? > > My test environment as below > Architecture is AMD Athlon 64 X2 Dual Core, and use rt3070 to test throughput. > Before not patch code, the throughput just only 5, 6M, but after patch, > throughput can achieve about 40M on open air. How about your test? I tried with rt2800pci on MIPS32 in AP mode (STA <- eth -> AP <- wifi -> STA2). An UDP iperf stream (STA -> STA2) was able to achieve up to 90Mbps while a TCP stream maxed out at around 70Mbps (before and after this patch). STA2 is an Intel HT20 11n client. Hmm, you've been testing on USB. Maybe that makes a difference? Nevertheless, such a performance drop on such a fast machine is likely caused by something different, no? Did you have any warnings in dmesg (due to watchdog timeouts for example)? Maybe the rate control algorithm made a wrong decision and used a low tx rate? > > Jay, Ivo, any objections against reverting this one? > > I agree to revert this one because this will cause tool small headroom of your mention. > We need to supply another patch when resolve all issue. Thanks. John, should I send a follow-up (with a nice description why it this is needed) or are you simply reverting this one? Thanks, Helmut -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
