Re: Throughput less than expected: madwifi 0.9.4 r4119

Can you share the math that leads you to believe that 8,000 packets is possible?  802.11 carries quite a bit of overhead.  This may help: http://www.oreillynet.com/pub/a/wireless/2003/08/08/wireless_throughput.html

I don't know how even your packet size distribution is, but plugging in different numbers, I come up with something like 6,000/s being theoretical max for you, and that's before needing to deal with contention for the medium.  I would guess that real-world over-the-air your limit would be something like 3,000/s without some drastic changes to the MAC and also tweaks to the PHY parameters.

Brian Prodoehl



-----Original Message-----
From: R.Mohan [mailto:[email protected]]
Sent: Tue 3/23/2010 1:22 PM
To: [email protected]
Subject: [Madwifi-users] Throughput less than expected: madwifi 0.9.4 r4119
 
Dear All,

I am experiencing only 25% 0f the expected throughput.

Athstats reports "tx frames discarded due to queue depth"

Can anyone help me to increase the queue sizes / resolve this problem.

I would like transmit 8000K plus frames per second. Frame sizes will range
from 78 bytes to 558 bytes.

Presently I am able to transmit approximately 2000 frames per second without
any tx frames being discarded.


Below is the report from athstats:

# ./athstats

84 tx management frames

1952979 tx frames discarded due to queue depth

1418 short on-chip tx retries

978 long on-chip tx retries

70 tx frames with no ack marked

303132 tx frames with rts enabled

303146 tx frames with short preamble

109 rx failed due to bad CRC

606261 rx failed due to frame too short

2347 PHY errors

    142 OFDM timing

    1 OFDM illegal rate

    1790 CCK timing

    21 CCK header crc

    326 CCK illegal rate

    67 CCK restart

9 periodic calibrations

rssi of last ack: 51

rssi of last rcv: 45

1 switched default/rx antenna



Thanks in advance

R.Mohan




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