Controlling Random Backoff Time

[Matteo Danieletto]

How Oleksij suggested you can read some bits of the backoff algorithm.

I think the algorithms is implemented in HW. 
On 7 Sept. I received the following reply about my question to retrieve the current contention window :

"Hm, that's something done in hardware. There's some bits in the DCU
that control what kind of contention backoff is used (fixed, random,
linear) but I don't know about reading the current contention value."

However, you want something like this:

for BE queue the range [CWmin , CWmax]  is  [15, 1023],
So the first step the backoff selects a random number between 0 and 15. If the medium is busy and other stuffs the CWmin becomes 31 and so on until CWmin reaches CWmax.
Do you want change the CWmin or exactly the value chosen between 0 and CWmin ?

Best,
Matteo
On Oct 6, 2014, at 10:22 AM, Greenstein, Adam <amg10c at my.fsu.edu> wrote:

> Thanks for replies,
> 
> To clarify I do mean that I would like to change the random value on the fly as Matteo suggested. I have searched the firmware source but have not been able to find it implemented anywhere yet.
> 
> Adam 
> 
> On Oct 6, 2014, at 1:09 PM, Oleksij Rempel <linux at rempel-privat.de> wrote:
> 
>> Am 06.10.2014 um 18:52 schrieb Matteo Danieletto:
>>> Hi,
>>> Olekesij, when you write backoff threshold do you mean CWmax, don't you?
>> 
>> I mean AR_D_MISC_BKOFF_THRESH and some more AR_D_MISC_ related bits. But
>> it dos not looks like it was ever used.
>> 
>>> Adam, what does control the random backoff mean? Change on the fly the random value chose? 
>>> 
>>> Also I was looking to find where is chosen the back off value, but I didn’t find the in source code . So I don’t know if the random backoff algorithm is implemented in firmware or inside the chipset .
>>> 
>>> Cheers
>>> Matteo
>>> 
>>> On Oct 6, 2014, at 7:57 AM, Oleksij Rempel <linux at rempel-privat.de> wrote:
>>> 
>>>> Am 05.10.2014 um 21:56 schrieb Greenstein, Adam:
>>>>> Hi all, 
>>>>> 
>>>>> Is it possible to precisely control the random backoff time within this firmware? If so how can this best be done? 
>>>> 
>>>> Hi,
>>>> 
>>>> this HW provide some control: backoff vs RTS/CTS mode; backoff threshold
>>>> and so on. If, it is what you need, that it should be possible to use
>>>> btw add it in to FW.
>>>> 
>>>> -- 
>>>> Regards,
>>>> Oleksij
>>>> 
>>>> _______________________________________________
>>>> ath9k_htc_fw mailing list
>>>> ath9k_htc_fw at lists.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/ath9k_htc_fw
>>> 
>>> 
>>> _______________________________________________
>>> ath9k_htc_fw mailing list
>>> ath9k_htc_fw at lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/ath9k_htc_fw
>>> 
>> 
>> 
>> -- 
>> Regards,
>> Oleksij
>> 
>