Re: [Madwifi-devel] Help with Reset functions

[Aditya B. <ay...@an...>]

After running these modifications for some time, I noticed that 
ar5212GetRateTable and ar5212_reset constantly get called. ANy ideas 
what could this be due to?

Thanks
regards,
Aditya Bhave


On 08/31/2010 05:31 PM, Aditya Bhave wrote:
> Hi Brett,
>
> I did as you suggested. I ran athstats in a loop printing to console
> every 1 second and it was showing a continuously increasing "tx failed
> due to many retries" for a simple ping.
>
> So I modified two parts of if_ath.c
>
> 1. ath_default_sifs: The time for 20MHz channels was 16. So I added code
> inside if(channel is 2GHZ) to make the time = 32 for 10MHz and time = 64
> for 5 MHz.
> 2. ath_default_slottime: The time for 20MHz channels was 20. So I made
> the time = 40 for 10MHz and time = 80 for 5MHz inside the if(current
> channel is 2GHZ)
>
> Inside ar5212_phy.c, inside ar5212GetRateTable(), I changed rt =
> &ar5212_11g_table for half and quarter rates.
>
> Setup: One AP-STA pair placed close to each other and transmitting at
> rate 12
> Lets call MSG1 = "tx failed due to many retries"
> and MSG2 = "long on-chip tx retries"
>
> Results:
> 1. When I ping from STA to AP, athstats for STA shows no MSG1s, but
> MSG2s increase for almost every ping packet sent. No increase in MSG1 or
> MSG2 in athstats for AP. Is this normal?
> 2. When I ping from AP to STA, a similar behavior is seen in athstats
> for AP.  A high packet loss (21%) is reported from ping.There is no
> increase in MSG1 or MSG2 in STA.
> 3. When I run iperf server on AP and iperf client on STA, throughput is
> reported to be around 3.5Mbps for rate 12, 2.5Mbps for rate 6 and
> 5.55Mbps for rate 12.
>
> Does the above look ok?
>
> Thanks for your help
> regards,
> Aditya Bhave
>
>
>
> On 08/25/2010 11:29 PM, Wright, Brett wrote:
>    
>> Hi
>>
>> Have a look at the output of athstats and I suspect you will see there
>> are a lot of "tx failed due to too many retries". If so this indicates
>> the acktimeout (as well as slot, sifs, etc) are wrong.
>>
>> If you have a look in if_ath.c for ath_default_slottime() and
>> ath_default_sifs(), etc (search for all occurrences of _HALF and
>> _QUARTER) and modify the times for these channels (every time the
>> channel is halved, double the time). Better to err on the high side with
>> all of these times until you get reliable comms...
>>
>> Brett
>>
>>
>>      
>>> -----Original Message-----
>>> From: Aditya Bhave [mailto:ay...@an...]
>>> Sent: Thursday, 26 August 2010 12:42 PM
>>> To: Wright, Brett
>>> Subject: Re: [Madwifi-devel] Help with Reset functions
>>>
>>> Hi,
>>>
>>> I did as you suggested, but the throughput is coming very low. When I
>>> put an AP and STA on a 10 MHz channel and configured them both to
>>> transmit at 12Mbps, Iperf reports a throughput of only 450 Kbps.
>>> Shouldnt it be close to 6 Mbps?
>>>
>>> When I put them on a 20 MHz channel, IPerf shows a throughput of
>>> 7.59Mbps. So 20 MHz seems to be working fine.
>>>
>>> Thanks
>>> regards,
>>> Aditya Bhave
>>>
>>>        
>>
>>      
>
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