On Sunday, January 29, 2012 04:03:41 you wrote: > On Sat, Jan 28, 2012 at 11:58 AM, Marek Lindner <lindner_marek@xxxxxxxx> wrote: > > On Sunday, January 29, 2012 03:17:32 Daniel Halperin wrote: > >> Adaptive RTS/CTS is important to control for interference---RTS/CTS is > >> there so that other Wi-Fi devices know not to interfere with your > >> flow. It may well be the case that this is not a major problem in > >> whatever your scenario you're working, Marek, but it makes a big > >> difference in a many bad corner cases. > > > > I am very well aware of what RTS/CTS is for and I am not against using > > it. However, having the rate algorithm overriding the user setting for a > > specific rate is extremely hard to grasp or debug. > > To give you an understanding where I am coming from: In our networks we > > experienced extremely variable throughput ranging from 30Mbit/s (single > > stream) to 0.2 Mbit/s in the next second. As you can imagine we were > > trying to figure out what was going on. After spending some time and > > losing hair I noticed that the RTS/CTS implementation of our driver > > (ath9k) is buggy. Every once in a while the nodes would "battle" each > > other with RTS/CTS packets. Strange enough for us, sometimes no RTS > > packets were sent and sometimes they would battle. All attempts to > > disable RTS/CTS for the mere sake of testing(!) was impossible. First I > > thought ath9k did not properly implement the "iw rts" setting but that > > wasn't the case. After losing more hair I realized that minstrel_ht, a > > rate control algorithm(!), was overriding my rts settings but not > > always(!). The only way to make RTS shut up was to apply the posted > > patch. > > Can you explain what the low-level behavior of an RTS/CTS "battle" is? > > Abstractly, the behavior you're describing sounds like a buggy driver > that doesn't obey overheard RTS or CTS packets. I certainly can explain it but this is for another thread and unrelated to the points raised before. Regards, Marek -- 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
