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Old 10-14-2007, 04:49 AM   #1
VisezTrance
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High latency on a Dell Wireless 1390


I got an nx7300 notebook with a Broadcom Corporation Dell Wireless 1390 WLAN Mini-PCI Card. I'm really not much of a gamer, but I like to play something on the LAN once in a while. However, once every few packages or so one is receveid quite late. Pinging my wireless router shows pings like these:

64 bytes from 192.168.0.1: icmp_seq=17 ttl=64 time=0.787 ms
64 bytes from 192.168.0.1: icmp_seq=18 ttl=64 time=0.786 ms
64 bytes from 192.168.0.1: icmp_seq=19 ttl=64 time=629 ms
64 bytes from 192.168.0.1: icmp_seq=20 ttl=64 time=0.779 ms
64 bytes from 192.168.0.1: icmp_seq=21 ttl=64 time=0.789 ms
64 bytes from 192.168.0.1: icmp_seq=22 ttl=64 time=0.786 ms
64 bytes from 192.168.0.1: icmp_seq=23 ttl=64 time=0.788 ms
64 bytes from 192.168.0.1: icmp_seq=24 ttl=64 time=0.784 ms
64 bytes from 192.168.0.1: icmp_seq=25 ttl=64 time=429 ms
64 bytes from 192.168.0.1: icmp_seq=26 ttl=64 time=0.772 ms
64 bytes from 192.168.0.1: icmp_seq=27 ttl=64 time=0.781 ms
64 bytes from 192.168.0.1: icmp_seq=28 ttl=64 time=0.780 ms
64 bytes from 192.168.0.1: icmp_seq=29 ttl=64 time=0.774 ms

Setting a higher fragmentation (ex. iwconfig wlan0 frag 2300) doesn't change this by much..
My only experience with wireless devices has been a few years ago on a desktop machine, but even though the AP was 1Km away, It worked really well..

I'm now going to post some data about my configuration:
The wireless router(D-Link DI-524):

Beacon Interval 50
RTS Threshold 2432
Fragmentation 2346
DTIM Interval 3
TX Rates auto
SSID broadcast Enabled

My machine:
(running 64bit Fedora7)
lspci | grep Wireless
10:00.0 Network controller: Broadcom Corporation Dell Wireless 1390 WLAN Mini-PCI Card (rev 01)

uname -r
2.6.22.5-76.fc7

Hope this is not happening because of my hardware.
Help would be really apreciated
 
Old 10-15-2007, 07:29 AM   #2
Hangdog42
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A few thoughts and questions, none of which may be on the mark:

- What driver are you using? FC7 did a number on a lot of ndiswrapper users and moved to a relatively new and untested native Linux driver called b43. Neither of these events is likely to be good for performance.

-Did you have this trouble prior to FC7 or is this the first Linux install on this rig?

-Broadcom chipsets are a pain in the patootie because of lack of support from Broadcom. If this is important enough you might consider picking up a supported wireless card. Intel and Atheros are two of the good players.

- The fact that you're running a 64 bit distro may play a role as well. I know ndiswrapper had some trouble with 64 bit drivers. I'm not sure how well b43/bcm43xx perform in 64 bits. On my rig, bcm43xx has an annoying tendency to break down under a heavy load.
 
Old 10-16-2007, 02:15 AM   #3
VisezTrance
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Quote:
Originally Posted by Hangdog42 View Post
- What driver are you using? FC7 did a number on a lot of ndiswrapper users and moved to a relatively new and untested native Linux driver called b43. Neither of these events is likely to be good for performance.
I'm using the bcm43xx driver. Had to unpack it with fwcutter and move it into lib/firmware.

Quote:
Originally Posted by Hangdog42 View Post
-Did you have this trouble prior to FC7 or is this the first Linux install on this rig?
Bought the notebook with freedos. The first and only OS installed is the 64 bit Fedora7, so I can't compare the windows native drivers performance..

Quote:
Originally Posted by Hangdog42 View Post
-Broadcom chipsets are a pain in the patootie because of lack of support from Broadcom. If this is important enough you might consider picking up a supported wireless card. Intel and Atheros are two of the good players.
No, it's really not that important I can live with it.

Quote:
Originally Posted by Hangdog42 View Post
- The fact that you're running a 64 bit distro may play a role as well. I know ndiswrapper had some trouble with 64 bit drivers. I'm not sure how well b43/bcm43xx perform in 64 bits. On my rig, bcm43xx has an annoying tendency to break down under a heavy load.
Haven't really noticed. The wireless performance, though poor, seems to remain constant ..

For now, I think all I can do is to keep an eye on the drivers changelog if any new version pops up...
 
Old 10-16-2007, 07:35 AM   #4
Hangdog42
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Since you're using bcm43xx, running a 64 bit OS probably isn't the culprit. However, I bet the bcm43xx driver is the root cause. Since it has been developed by reverse engineering, it is bound to have a few bugs and it doesn't support all Broadcom chipsets as well as others. The 4318 in particular is known to have problems.

One thing to keep in mind if you decide to upgrade is that wireless support in Linux is undergoing a large transition. The underlying wireless stack is being changed (I believe the changes started in the 2.6.22 kernel) and it isn't always going smoothly. So make sure you pay attention to the kernel changelogs around bcm43xx and don't just upgrade blindly.
 
  


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