> Hello and sorry for bothering you again.
> Thanks for your reply. I did what you told me about checking retries with
> wireshark and the stats turned to be the same as my printk()s. But my
> problem was this: How accurate these stats are at t= say t0. I mean when I
> get ts->ts_longretry = 25 is it actually 25 OR am I getting some staled
> numbers and the real value of longretry is, for example, 29? Because as I
> observed, also the packets wireshark displays are some seconds older than
> those my printks show! I get 31 retries in my printks but the WS shows me
> 27. And after a few seconds it reaches to 31.
> And when you say estimation of backoff, You actually made it to guess the
> CW value at a given point of time? And You used just ts->ts_long/shortretry
> or you read some other values directly from some REGS? If the first one
> holds, would you suggest me to count on these stats for my Backoff emulation
> attempt?
> Thank you in advance!
> PS: I sent a mail with the subject: "[Madwifi-devel] ath_tx_processq and
> long_short retry " but Sritej' s reply came under this subject! You may
> receive this mail twice ( and sorry for that) because the first one, as
> madwifi list informed me, is waiting for moderation approval due to its too
> big size. So I re - send this mail with having cut some irrelevant to my
> problem subjects and texts off. Sorry again!
>
> 2010/5/21 sritej s <sritejv@gmail.com>
>
>> I estimated backoff based on these statistics for my project a year back
>> and I got a reasonable estimate.As Mohammad pointed out ,Wire shark is a
>> good tool to verify the retry count.Just check for the retry field in the
>> MAC header. Short retries are for RTS/CTS .Long retries are for the data
>> packets..
>>
>> Thanks,
>> Sritej
>>
>>
>>
>>> Message: 1
>>> Date: Mon, 17 May 2010 22:29:00 +0300
>>> From: Mohammad Abdelhadi <mo.jaser@gmail.com>
>>> Subject: Re: [Madwifi-devel] ath_tx_processq and long_short retry
>>> To: Nicolas Barati <nicolas.barati@gmail.com>,
>>>
madwifi-devel@lists.sourceforge.net
>>> Message-ID:
>>> <AANLkTinWMaMgg18k8xg6KVjcNnyw1zGw_Sgnfrh6R-8T@mail.gmail.com>
>>> Content-Type: text/plain; charset="iso-8859-1"
>>>
>>> On Mon, May 17, 2010 at 8:00 PM, Nicolas Barati <
>>> nicolas.barati@gmail.com>wrote:
>>>
>>> > Hello all,
>>> > In my research on madwifi 's back-off, eventually I got convinced that
>>> > there is no way to see the current contention window 's value. So I
>>> turned
>>> > to something else. I tried to disable backoff and then emulate a
>>> backoff
>>> > scheme of my own on driver level. I disabled backoff by adding this:
>>> > qi.tqi_qflags |= HAL_TXQ_BACKOFF_DISABLE; to ath_txq_setup().
>>> > Now I need a measure based on which my backoff emulation will
>>> > increase/decrease my_CW. I found in ath_tx_status these variables:
>>> > ast_longretry / ast_shortretry. I saw that these values are incremented
>>> > only in ath_tx_processq() which is called from ath_tx_tasklet() or
>>> > ath_tx_tasklet_q0(123)(). I read here :
>>>
http://www.makelinux.net/ldd3/chp-7-sect-5.shtml
>>> > about tasklet function and what I understood is that these functions
>>> are
>>> > some kind of timer/scheduling functions.It sayes: "By scheduling a
>>> tasklet,
>>> > you simply ask for it to be executed at a later time chosen by the
>>> kernel".
>>> > If It is so and these tasklet functions are called just some time in
>>> the
>>> > future (regarding current kernel time) and the long/shortretry
>>> variables
>>> > are incremented only through ath_tx_processq when they are called, how
>>> > accurate these variavles are in regard of the real state of retries.
>>> Are
>>> > they to be trusted? Would you suggest that I consider these variables
>>> for my
>>> > emulation??? And one more question, is disabling backoff done like how
>>> I
>>> > said I did it above? And is there any way to see if it is indeed shut
>>> and
>>> > not enabled again in some other part of the code or some time during
>>> the run
>>> > time of the driver?
>>> >
>>> > Thank you!
>>> >
>>> >
>>> >
>>> ------------------------------------------------------------------------------
>>> >
>>> >
>>> > _______________________________________________
>>> > Madwifi-devel mailing list
>>> >
Madwifi-devel@lists.sourceforge.net
>>> >
https://lists.sourceforge.net/lists/listinfo/madwifi-devel
>>> >
>>> >
>>> Hi,
>>>
>>> ath_tx_tasklet() is responsible to update information of each
>>> transmitted
>>> packet, please take a look on
>>>
http://mesh.calit2.net/whzhao/madwifi_summary.pdf
>>> <http://mesh.calit2.net/whzhao/madwifi_summary.pdf>
>>> - how accurate these variavles are in regard of the real state of
>>> retries. Are they to be trusted? Would you suggest that I consider these
>>> variables for my emulation???
>>>
>>> Well, to test the accuracy of these variables, you can use a Network
>>> Analyzer like Wireshrk, to see how many times a packet has been
>>> retransmitted,
>>>
>>> I think that (ts->ts_longretry) is responsible ot store the number of
>>> long
>>> reties for each packet, but any way, you can test that and see by your
>>> self.
>>>
>>> Hope this helps.
>>>
>>>
>>> Regards,
>>> --
>>> Mohammad Jaser Abdelhadi
>>>
>>> ----------------------------------------------------------------------------
>>> Communications Engineering-Senior Student
>>> Princess Sumaya University for Technology
>>> Mobile: +962777030924
>>> Email:
moh.jaser@ieee.org \
mo.jaser@gmail.com
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