Hi USB guru,
Here is the update on my testing. I went out and bought 2 more USB
wireless devices
with different chipset. The original device is DLink DWL-G122 with
Ralink chip
and new device is DLink DWL-AG132 which has Atheros chip. This is to
make sure
that I am using different driver for each device. I then hooked both
DWL-G122 and
DWL-AG132 up to a PC and installed their driver and did the same to
another PC.
Run one channel at a time with ttcp, speed is good as expected. Again,
when I ran
both of them simultaneously, their speed drop again, same result as my first
experiment.
I couldn't explain why when I ran Wireless + Flash devices simultaneous,
the wireless
speed didn't drop (Hope I didn't do anything wrong here. Basically, I
just copied a
large file to Flash device (cp command followed by sync command) and at
the same
time run "ttcp"). But when I ran 2 different Wireless devices,
their speed dropped.
Any suggestion?
BTW, Alan, do you have chance to look at the usbmon files I sent you? I
tried to post my
zip file to the forum but got rejected. I browse through them and
didn't spot anything.
Would anyone be interested to look at it?
I wish I have USB analyzer to look at the performance/usage graph on the
bus.
Unfortunately, this is my home project and I don't want to spend $3k on the
analyzer just for this. Any help or suggestion is appreciated.
Thanks,
Adisorn.
Alan Stern wrote:
On Tue, 16 May 2006, aermongk wrote:
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=480 MxCh= 0
D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=2001 ProdID=3c00 Rev= 0.01
S: Manufacturer=ANI
S: Product=802.11g WLAN Adapter
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=300mA
I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=rtusb
E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
According to this, the MxPS value for endpoint 1 is 512. Not 64.
D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
^^^^^^^
How about this value? Isn't this is what configured on the device?
That is the MaxPacket value for endpoint 0. The last two lines above show
the MaxPacket values for endpoint 1.
I did a printk of this value for both endpoint 0 and 1 right at the
beginning of probe function and the values are 64. That was the reason
that I mentioned 64. I did try to increase the value to 256, again
from inside probe function, but it didn't help.
You must not change these values. They are defined by the device, not by
the kernel.
BTW, I also tried usbmon as you'd suggested. Do you mind looking at
the files that I've captured? If you don't mind I will send to you
directly. There are 3 files that I captured - one for channel 6,
one for channel 11, and last is chan 6 and 11 running simultaneously.
The first 2 files are ~575K and last is ~1.12M. I am still trying
to figure out the values produced by usbmon and what are these
timings meant. You probable can spot problem much faster than I do.
Please let me know if I can sent to you.
Try sending just the first 100 KB of the channel 6 file and the first 200
KB of the dual-channel file. You can gzip them if you want; that should
shrink them quite a bit.
Alan Stern
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