On 2013-03-01 12:18 PM, Mohammed Shafi wrote: > Hi Felix, > > On Fri, Mar 1, 2013 at 3:59 PM, Felix Fietkau <nbd@xxxxxxxxxxx> wrote: >> On 2013-03-01 11:22 AM, Adrian Chadd wrote: >>> On 1 March 2013 02:14, Felix Fietkau <nbd@xxxxxxxxxxx> wrote: >>> >>>>> Having access to schedule which peer and how much to send to each peer >>>>> would be nice. Stuff like "peer X only can have up to x ms in this WME >>>>> class this round", so you don't have a busy, close peer monopolising >>>>> the air. It also means you can start doing smart things with far away >>>>> peers who retransmit a lot - they're likely tying up a lot of airtime. >>>>> >>>>> None of this is new. It's just, you know, new to open source. :-) >>> >>>> In my opinion this doesn't really belong into a rate control module. >>>> There should be a tx scheduling API to take care of this. Before I >>>> implement something like this, I plan on exposing all per-station driver >>>> queues to mac80211. This is necessary for a few other things anyway, >>>> e.g. unifying software aggregation logic and fixing its buffer management. >>> >>> Sure, but then some more clever tricks end up being difficult to >>> implement. For example, knowing if a client is tying up too much >>> airtime at the given rate and whether to back them off for a bit. Or >>> to use smaller aggregation limits for certain clients because your'e >>> trying to be "fairer" when trying to keep latency low. That kind of >>> thing. >>> >>> I think "rate control" should likely be expanded to "tx scheduling" as >>> a whole, rather than sitting as a separate thing that just selects the >>> rate for a node who has already been chosen to transmit. >> Even with client airtime use, I still don't see how tx scheduling and >> rate control belong together. In my opinion, the rate selection should >> not be based on client airtime usage or the current load, as it can >> optimize for throughput/airtime ratio without it. >> > > Algorithm folks and Engineers had spent considerable time on ath9k rate control. > Wouldn't be a great idea to remove it completely, We can have it optional. > With lot of throughput tests ran over internally and with the test > team verification, > it wouldn't be fair to throw it away. Regardless of how much time was spent tuning it, it still has a really bad design, bad implementation and a number of practical issues. It seems to be tuned entirely for artificial benchmarks in clean air. It also starts with a very high rate without having proven that it works. I don't think anybody is going to fix all of these issues, and even if somebody does, it would invalidate pretty much all of the tuning/testing that went into this code. - Felix -- 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
