This may not be the first time that you've heard
this. It's about WEP performance with this driver.
When in (b) mode, performance drops to less than
1/4 of the unencrypted mode. Using a LinkSys 802.11b AP, throughput goes
from 525 KB/s to 96 KB/s with no other variable other than turning WEP
on/off. In (g) mode, using a DLink 624 AP,
I go from 1.2 MB/s to 740 KB/s which is
almost half. In both cases, the stationary computer is WIRED to the AP to leave
the band open for the wireless node.
I have looked into the WEP encryption code in
if_ieee80211subr.c and I don't see anything that strikes me as terribly
inefficient. I have compared it to the linux-wlan code and it looks similar
enough, save for the fact that they use a statically defined CRC table, while
the madwifi driver initializes it (once, I hope).
So what could be causing this? I don't have a lot
of experience in kernel land, but I would be willing to dig my hands into it if
you can provide some pointers. Anyone care to comment? Sam?