Bug 81571

Summary: iwlwifi: Lack of TX AMPDU severely impacts performance
Product: Drivers Reporter: haarp (main.haarp)
Component: network-wirelessAssignee: drivers_network-wireless (drivers_network-wireless)
Status: CLOSED WILL_NOT_FIX    
Severity: normal CC: ilw, linville
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 3.12 Tree: Mainline
Regression: No

Description haarp 2014-08-02 17:37:04 UTC
Hello,

I've recently been battling a performance regression on my Wifi, until I figured out that it was a driver issue. To be precise, it's a regression introduced by this commit:

iwlwifi: disable TX AMPDU by default for iwldvm, 205e2210daa975d92ace485a65a31ccc4077fe1a

Predictably, setting 11n_disable=8 restores performance. Without it, my throughput falls by almost an order of magnitude to 802.11g levels!

This can't be intended. Even as a trade-off for increased stability (which is what I understand this commit is for), this seems like a bad default.

Additionally, it's very hard to diagnose (took me many hours).

Can there be a better way?
Comment 1 Emmanuel Grumbach 2014-08-04 17:11:45 UTC
I can't see another way.
I can't really debug the FW issues and most people care more for reliability than performance.