Chenchong's work on net80211_ratectl

[Chenchong Qin]

Hi!

Here is some updates.

Another member is added to ieee80211_rc_info to record value of the maximum
aggregate size. Then, in aggregation scenario, ratectl algo can inform
aggregation selection code of proper maximum aggregate size.

Per-vap ratectl statistics is exported through sysctl. When
ieee80211_ratectl_init() is called, this statistics api is attached. It's
convenient to implement the per-device api -- just traverse the vap list
and call per-vap api for each vap. But, we know that ratectl of net80211
provides service to vap-granularity object, not to device directly. So, is
it more suitable to implement the per-device api in device driver (i.e.
attach per-device api when attaching the device)?

Code will be posted later.

Thanks!

Chenchong


On Thu, Sep 12, 2013 at 2:05 AM, Adrian Chadd <adrian at freebsd.org> wrote:

> Hi,
>
> For now, yes, you have to assume that you won't always get a response for
> a rate lookup. The buffer may be sent with NOACK set, it may be deleted
> during a channel change or scan, etc.
>
> And yes - the rate control lookup stuff for aggregate frames is a bit
> messy. It would be nice for the rate control code to return the rate _and_
> the maximum aggregate size, in case the aggregation selection wants to cap
> how long frames are at the given choice.
>
>
>
> -adrian
>
>
>
> On 11 September 2013 10:29, Chenchong Qin <qinchenchong at gmail.com> wrote:
>
>> Hi!
>>
>> I've added some aggregation support here!
>>
>> At first I intend to pass subframe informations(nframes, per-subframe
>> length etc.)
>> to the ratectl api. But it seems to be a paradox that rate lookup must be
>> performed
>> before the ampdu is formed (aggregation limit based on the rate control
>> decision
>> is need) and subframe informations can be obtain only after the ampdu is
>> formed.
>> So, I add a new ieee80211_rc_info flag to ieee80211_ratectl to let it
>> distinguish
>> aggregation and non-aggregation scenarios. If rate lookup is called in an
>> aggregation
>> scenario, this flag is set. Then, ratectl algo knows that it's now
>> finding rates for an
>> ampdu and the framelen which records len of the first frame can be
>> ignored. When
>> it comes to complete period, tx status that shows number of subframes
>> been sent
>> and number of subframes been successfully received is passed to the
>> ratectl api.
>>
>> I also get a question here - whether one tx that doesn't perform rate
>> lookup will call
>> the complete procedure?
>>
>> Thanks!
>>
>> Chenchong
>>
>>
>> On Sun, Sep 8, 2013 at 11:18 PM, Chenchong Qin <qinchenchong at gmail.com>wrote:
>>
>>> Hi!
>>>
>>> I've added the common ratectl state as an mbuf tag!
>>>
>>> After days of frustration (compile errors, boot failed, kernel panics,
>>> suddenly kernel freezing...), it seems that ath now can use 11n-aware
>>> net80211 ratectl api to do rate control. Attachment[0] is the diff of
>>> modifications to dev/ath. Changes to net80211 is minor this time. Just add
>>> some debug msgs to it. Please reference my gsoc svn repo<https://svnweb.freebsd.org/socsvn/soc2013/ccqin/head/>
>>> .
>>>
>>> It's worth mentioning that sometimes the kernel will "freezing" (it
>>> looks like all things stop working, screen is freezing, keyboard and mouse
>>> are not responding) after wireless stuff start working for a while. At
>>> first, I consider it caused by my modification to ath. But this strange
>>> thing can also happen in a head kernel (r255382). Attachment[1] is some
>>> useful messages just before it happens. By the way, I use a AR9227 device.
>>>
>>> And, I found that, for aggregation scenario, ath gathers tx information
>>> and update the ratectl states. So, what we can do to net80211 to let it
>>> support aggregation?
>>>
>>> Thanks!
>>>
>>> Chenchong
>>>
>>>
>>> On Tue, Sep 3, 2013 at 9:29 AM, Chenchong Qin <qinchenchong at gmail.com>wrote:
>>>
>>>> OK!
>>>>
>>>> Thanks! :-)
>>>>
>>>> Chenchong
>>>>
>>>>
>>>> On Tue, Sep 3, 2013 at 1:56 AM, Adrian Chadd <adrian at freebsd.org>wrote:
>>>>
>>>>> Hi!
>>>>>
>>>>> You can declare an mbuf tag and use that. Look at M_TXCB in net80211
>>>>> and how mbuf tags are added.
>>>>>
>>>>> I've long thought about adding a net80211 mbuf tag to represent -all-
>>>>> of the tx related state - TX callback, rate control, rate completion,
>>>>> aggregation state, retry count, etc. That way all the drivers can use it.
>>>>>
>>>>>
>>>>>
>>>>> -adrian
>>>>>
>>>>>
>>>>
>>>
>>
>