[SOLVED] rtl8192se Slow Performance

drelyn86 · 2011-03-08 15:52:30

I'm having some interesting wireless issues with my new System76 Starling3.

The Problem: All wireless network traffic is very slow on this machine.

System Info

wireless chipset: Realtek RTL8191SEvB
package installed: AUR/rtl8192se (http://aur.archlinux.org/packages.php?ID=34281)
* The current version of rtl8192se is 2.6.0019.1207.2010-1, but the AUR comments suggest the more stable version is 2.6.0015.0127.2010. I've compiled both versions without any noticeable differences in performance (however, dmesg reports a lot less wireless wake/sleep events when running the stable version).
wireless backend: using wicd, but have tried networkmanager with no noticeable differences
wireless security: WPA2
wireless channel: my router is the only one using channel 1 in my area... other wireless devices on my network don't seem to be affected anyway

Troubleshooting Info

I'm not at my machine right now, so I'll update the console output later, where applicable. For now I'll just describe my general results.

dmesg reports a lot of stuff about wireless wake and sleep... much more often when using the most recent driver. I'll definitely need to paste that later, since it might be useful.

ping -c 20 192.168.1.1

Summary: My pings average about 350ms, sometimes max at up to 3000+ms, and I usually get about 10%-45% dropped packets. Other wireless devices on the network are able to ping the router with an average of 4ms with 0-5% dropped packets.

sftp user@mediaserver
sftp> get archlinux-2010.05-core-i686.iso

Summary: This averages at about 30KB/s and even drops down to about 5KB/s. Other wireless devices on the network achieve about 2.1MB/s.

Tried this: Moving really close to the router
No improvement

Tried this: Making sure all other network devices are either powered off or idle
inconclusive results
For a while I thought there was an issue with my wii streaming netflix as I was first trying to figure this out... when I turned off the wii, there appeared to be an improvement, but later I made sure all devices on the network were either turned off or not doing any type of network traffic and I was still getting very poor performance.
It's probably worth looking into more, but my other laptop (broadcom chipset) doesn't seem to be as drastically affected when there's a lot of traffic over the network.

Tried this: Removing the battery
I don't know why I tried this or where I read the suggestion... getting desperate, I guess.
No improvement

Tried this: Disable acpi by appending "acpi=off" to the kernel entry in /boot/grub/menu.lst
The network issues seem to disappear completely when I do this. I get 0% dropped packets on ping tests, and executing the same sftp transfer as above maintains a consistent 2.2MB/s. However, I can't run my machine like this all the time, for obvious reasons.

One of the suggestions in the AUR/rtl8192se comments is to execute "iwpriv wlan0 set_power 0". This doesn't seem to affect performance, but it does stop the wireless sleep/wakeup events reported by dmesg. I've also tried "iwconfig wlan0 power off" without any improvement.

What does this do?: "acpi=copy_dsdt"

I found this thread, which appeared to be more of an issue of the OP's machine not booting while using this same driver.
https://bbs.archlinux.org/viewtopic.php?id=102893

It looks like he solved his issue by adding "acpi=copy_dsdt" to his boot entry. I want to give this a try... but I'm not able to find any information to what this actually does... so I wanted to find out before I tried it. Or just let me know if it's generally safe to use, and I'll see if it helps anything.

Note: I'm still not exact sure what this does, but I tried it later, and it did not help. It appears to be a good fix for many Toshiba laptops that have trouble booting...

Last edited by drelyn86 (2011-03-09 12:18:55)

drelyn86 · 2011-03-09 01:07:52

I gave the copy_dsdt thing a shot... no improvments.
I'm really lost... trying different arguments for iwpriv and iwconfig... not really getting anywhere.

Here's an example of the output from dmesg:

rtl8192_hw_sleep_down(): RF Change in progress!
rtl8192_hw_sleep_down(): RF Change in progress!
rtl8192_hw_sleep_down(): RF Change in progress!
rtl819xSE:Err RX pkt len = 0x17

rtl8192_hw_wakeup(): RF Change in progress! schedule wake up task again
rtl8192_hw_wakeup(): RF Change in progress! schedule wake up task again
rtl8192_hw_wakeup(): RF Change in progress! schedule wake up task again
LPS leave: notify AP we are awaked ++++++++++ SendNullFunctionData
LPS leave: notify AP we are awaked ++++++++++ SendNullFunctionData

So with this information, and the fact that the wireless performs wonderfully with acpi=off, it's probably safe to say this is due to some power-management capabilities of the wireless card... I just don't know how I can fix this, as I don't know of, and can't find any other options for the power management of wlan devices.

drelyn86 · 2011-03-09 03:08:57

I tried recompiling the modules and running under kernel26-lts. No improvements

I can start looking into getting the wireless working under ndiswrapper, but this may be a last resort...

Last edited by drelyn86 (2011-03-09 03:09:31)

drelyn86 · 2011-03-09 04:26:40

This is ridiculous... I have no idea how ACPI has anything to do with this... but I've solved my problem.

In one of the many random illogical fixes I tried... I switched the channel on my wireless router.
It was on channel 1, which I thought should have been ok, since I was the only ESSID in my area using that channel. I'm now on channel 9, and everything is running perfect. Ping tests are consistently < 2ms with 0% packet loss, and the sftp transfer reaches almost 3MB/s.

Now I just want the past 2 evenings back!

Well... hopefully this thread helps someone out in the future...

Last edited by drelyn86 (2011-03-09 04:43:14)

jededale · 2011-04-17 20:27:58

Sorry for the stupid question but how exactly do you change the cchannel?

aditya.shevade · 2011-08-13 17:48:47

Same problem still there after Kernel 3. I installed the latest 8192ce drivers from AUR (thinkpad T420 laptop). The problem of slow and ever dropping connections persists. I might have to switch back to 2.6.39 >.<
Have tried using the built in drivers, the AUR package, the package provided by the manufacturers but it only happens in my home - around 20-30 networks around, probably causing interference but if I turn on my phone wireless tether then I don't face such problems (in the same area).

Arch Linux

#1 2011-03-08 15:52:30