poor PCMCIA network performance

[rlk at alum.mit.edu (Robert L Krawitz)]

I use two network cards in my Dell Inspiron 8000 (PIII-700): a 3Com
3CCFE574BT and a Linksys wireless card.  With the 3Com card (which is
a 10/100) I never get better than 1.4 MB/sec (about 12 Mb/sec), even
when the card is in 100 Mb mode (at some point in the past the limit
was about 2.5 MB/sec).  At that rate, top shows my CPU utilization
pegged at about 100%, even doing a simple ftp.  I know the card
doesn't do DMA, but that's rather slow even for a PIO transfer.  These
cards have been around for ages; I don't think people would have been
too satisfied with 400 KB/sec saturating a 200 MHz system.

On the Linksys card, I likewise never get more than about 250 KB/sec,
even if the computer is right next to the WAP and the link quality is
92/92, suggesting that I'm also hitting up against a hard limit.  The
WAP is connected to my main system via the motherboard ethernet, which
I know from other means (when I was transferring data from my previous
system to the current one) has no trouble maxing out at 10 MB/sec
(that ethernet does DMA).

eth1      IEEE 802.11-DS  ESSID:"..."  Nickname:"..."
          Mode:Managed  Frequency:2.437GHz  Access Point: 00:04:5A:CF:F3:B1
          Bit Rate:11Mb/s   Tx-Power=15 dBm   Sensitivity:1/3  
          Retry min limit:8   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality:26/92  Signal level:-76 dBm  Noise level:-149 dBm
          Rx invalid nwid:0  invalid crypt:0  invalid misc:0

I'm running SuSE 7.3 on both systems, with a recompiled kernel based
on kernel-source-2.4.16.SuSE-24.  I'm not (or don't think I am)
running a firewall or NAT on the laptop, despite what's in the module
list.  I've had no luck finding anything on the net.  Modules that
look like they should be relevant are:

orinoco_cs              4352   1
orinoco                27312   0 [orinoco_cs]
hermes                  3200   0 [orinoco_cs orinoco]
af_packet              11616   0 (autoclean)
appletalk              18832   0 (autoclean)
ipx                    15008   0 (autoclean)
ds                      6384   2 [orinoco_cs]
yenta_socket            8368   2
pcmcia_core            37568   0 [orinoco_cs ds yenta_socket]
ipv6                  124480  -1 (autoclean)
iptable_nat            12560   0 (autoclean) (unused)
ip_conntrack           12656   1 (autoclean) [iptable_nat]
iptable_filter          1728   0 (autoclean) (unused)
ip_tables              10304   4 [iptable_nat iptable_filter]

Suggestions?

-- 
Robert Krawitz <rlk at alum.mit.edu>      http://www.tiac.net/users/rlk/

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at uunet.uu.net
Project lead for Gimp Print/stp --  http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton