Hey folks, So first of yes, the title could probably be considered "link bait" but honestly I'm fed up with iwlwifi and 11n networks that I consider this the most friendly subject that I can come up with. Anyway, lets get to the problem. I'm currently using a Thinkpad T520 running Arch Linux with kernel version 3.10.10-1. The particular wireless chipset of this laptop is a Centrino Wireless-N 1000 (Condor Peak). Ever since day 1 of using this laptop/chipset I've been having issues with 802.11n (in combinatio with the iwlwifi driver). Either I couldn't connect to a network at all (e.g. with my previous router) or performance would be hilariously slow up to the point where even 11b would be faster. Now that I have a new router (Asus RT-N66U, I can recommend it to those that want a decent router) I can at least connect, sadly the performance of my laptop is still anything but decent. What happens is that I can connect and use 11n fine for a bit. However, as time progresses the amount of excessive retries (as reported by `iwconfig`) fills up up to a point where the bitrate plummets to 1MB/sec and my log files start filling up with iwlwifi errors such as the one seen here: http://git.io/7JLTLw (links to gist.github.com). When this happens download speed also drops to around 1MB/sec (due to the bitrate) and response times go up. Before Linux 3.10 (Linux 3.9 for example) I could work around this issue by either reconnecting to the network or reloading the driver. With Linux 3.10.10 however it seems this doesn't do anything. In this particular log entry you can see me reconnecting to the network on Sep 02 21:41:21 with the same errors popping up moments later. This particular problem isn't exactly new either, similar (or maybe even the same) issues have been reported before: * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1034740 * https://bugzilla.redhat.com/show_bug.cgi?id=804259 * http://bugs.centos.org/view.php?id=6305 This would suggest to me that the issue is an actual driver issue instead of being some race condition that only occurs on specific hardware configurations. The common "fix" for this problem is to disable 11n on driver level. This isn't exactly a fix however, it's simply sticking your head in the sand and ignoring it. I suppose that for a lot of people this is good enough since their internet speeds don't require 11n. In my case however I'm using a fibre internet connection and I'd like to actually be able to use the full 10 MB/sec via the wifi connection (it's 2013 after all). To cut a long story short, what I'd like to know is the following: 1. Is this a known issue and if so, when can we expect a fix? 2. What can I do to help out with this? Actually writing kernel code is way over my head but I'd love to help out by testing patches as much as my schedule permits. Some extra hardware/software information in case it helps: uname output: Linux tuxbook 3.10.10-1-ARCH #1 SMP PREEMPT Fri Aug 30 11:30:06 CEST 2013 x86_64 GNU/Linux The operating system is Arch Linux 64bit. The network management software used is Network manager 0.9.8.2-1 which uses wpa_supplicant 1.4-2 and dhcpcd 6.0.5-1 under the hood. In total there are about 29 networks (mine included) in my area, these operate on channels 1, 3, 4, 5, 6, 7, 8, 11 (some networks operate on the same channel). My own network is the only one that runs on channel 5, changing channels doesn't have any affect on the performance in any noticable way. If there's any more info that I could/should provide I'd be happy to do so. Yorick Peterse -- 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
