Thread (37 messages) 37 messages, 9 authors, 2013-03-03

Re: [RFC] ath9k: remove ath9k_rate_control

From: Paul Stewart <hidden>
Date: 2013-02-08 16:38:37

Could you share some of the test results?  I know with ChromeOS when
we switched to 3.4, the first thing that tipped us off to the fact
that we had inadvertently switch to minstrel was that our RvR
throughput values had dropped significantly.  Has anyone done an RvR
comparison between minstrel and the ath9k internal rate control
lately?

--
Paul

On Fri, Feb 8, 2013 at 6:16 AM, Felix Fietkau [off-list ref] wrote:
On 2013-02-08 3:08 PM, Sujith Manoharan wrote:
quoted
Felix Fietkau wrote:
quoted
In many tests throughput with ath9k_rate_control has been shown to be
worse than with minstrel_ht (the mac8021 default RC).

This module also has some other problems, like starting to use the
highest possible rate early in the connection, causing problems with
reliability of connection/authentication attempts.

It also has a much more limited search space, ignoring many potentially
useful rates, caused by the design decision to operate on a sorted rate
set with the assumption that higher rates are always more unreliable
than lower rates. In some scenarios this assumption is not true, and
this can cause it to fall back to a really bad rate.

minstrel_ht has been tested extensively in AP and client mode by lots of
users (mostly in the OpenWrt project, where it has been the default for
years).
I don't think managed mode would have received much testing in OpenWRT.
I know quite a few people that use directional links with 4-addr
AP/Station. I also know a few people that put up some devices that roam
between multiple APs. Obviously it doesn't receive as much testing as AP
mode, but there are some active users stress testing it.

- Felix

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