rt2x00 (rt61pci) TX rate

Live forum: http://rt2x00.serialmonkey.com/viewtopic.php?t=5028

xodr

05-10-2008 09:41:57

Hi again!

I have this question what is the maximum packet sending rate that I can achieve using rt2x00 rt61pci ? I know this is a weird one and depends on a myriad of things, nevertheless here are my specs

- WLAN card CNET-CWP854 (w/ Ralink chipset)
- RAM 1 GB
- CPU Intel Pentium M 2Ghz.

The system runs on debian linux and it's not loaded at all. The only task running is the task that sends UDP packets.

Now my question is

Whenever I call (I basically want to send three packets almost at the same time)

[code2y1gtqi5]result = sendto(sid1, buffer, result, MSG_DONTWAIT, (struct sockaddr *)&addr1, addrLen);
result = sendto(sid2, buffer, result, MSG_DONTWAIT, (struct sockaddr *)&addr2, addrLen);
result = sendto(sid3, buffer, result, MSG_DONTWAIT, (struct sockaddr *)&addr3, addrLen);[/code2y1gtqi5]

There is at least 1 millisecond latency between sent packets. (I sniff them using wireshark from another box) Buffer size is set to 0. What can be the cause of this? Have you run any such tests? If yes what were your results? I'm not merely interested in throughput (transmission rate in terms of bps). I'm interested the [b2y1gtqi5]maximum rate at which I can send UDP datagrams[/b2y1gtqi5] (and my packets are very small like 2 to 10 bytes).

Checking my kernel.log I see that debug is turned on in the rt2x00 driver. Can this be the cause? My log is filled with lines like


[code2y1gtqi5]Oct 5 19:07:11 debian kernel: phy1: TX to low-level driver (len=66) FC=0x0050 DUR=0x013a A1=00:08:a1:b7:aa:bc A2=00:08:a1:b7:aa:a5 A3=00:08:a1:b7:aa:a5
Oct 5 19:08:13 debian kernel: phy1: TX to low-level driver (len=66) FC=0x0050 DUR=0x013a A1=00:08:a1:b7:aa:bc A2=00:08:a1:b7:aa:a5 A3=00:08:a1:b7:aa:a5
Oct 5 19:09:15 debian kernel: phy1: TX to low-level driver (len=66) FC=0x0050 DUR=0x013a A1=00:08:a1:b7:aa:bc A2=00:08:a1:b7:aa:a5 A3=00:08:a1:b7:aa:a5[/code2y1gtqi5]


--------------------------------------------
Here is the output of modinfo. As far as I remember I am using some version of linux-wireless project.

[code2y1gtqi5]author: http://rt2x00.serialmonkey.com
version: 2.1.5
description: Ralink RT61 PCI & PCMCIA Wireless LAN driver.
firmware: rt2561.bin
firmware: rt2561s.bin
firmware: rt2661.bin
license: GPL
vermagic: 2.6.24.5-Xenomai-2.4.3 preempt mod_unload PENTIUMM
depends: rt2x00lib,rt2x00pci,eeprom_93cx6
alias: pci:v00001814d00000301sv*sd*bc*sc*i*
alias: pci:v00001814d00000302sv*sd*bc*sc*i*
alias: pci:v00001814d00000401sv*sd*bc*sc*i*
srcversion: 87D3C3CFFE8283D5053ABF8[/code2y1gtqi5]

xodr

06-10-2008 10:31:24

In addition to the above post

Is there *any* way to change the parameters (such as DIFS, SIFT, CW, etc... ) of the WLAN card by modifying the driver or by some other means to control the medium access latency ?[/color3c5rpplx]

I've found that 2500pci.h encapsulates many definitions that I'm interested in. I will play around some settings tonight...

regards.