Network speed Linux-2.6.10

[linux-os]

Conditions:

Intel NIC e100 device driver. Two identical machines.
Private network, no other devices. Connected using a Netgear switch.
Test data is the same thing sent from memory on one machine
to a discard server on another, using TCP/IP SOCK_STREAM.

If I set both machines to auto-negotiation OFF and half duplex,
I get about 9 to 9.5 megabytes/second across the private wire
network.

If I set one machine to full duplex and the other to half-duplex
I get 10 to 11 megabytes/second transfer across the network,
regardless of direction.

If I set both machines to auto-negotiation OFF and full duplex,
I get 300 to 400 kilobytes/second regardless of the direction.

I thought the problem must be the switch so I substituted a
cross-over wire. The problem gets worse, maybe 50 to 100
kilobytes (random bursts) per second.

`lspci`

00:00.0 Host bridge: Intel Corp. 82865G/PE/P DRAM Controller/Host-Hub Interface (rev 02)
00:01.0 PCI bridge: Intel Corp. 82865G/PE/P PCI to AGP Controller (rev 02)
00:1d.0 USB Controller: Intel Corp. 82801EB/ER (ICH5/ICH5R) USB UHCI #1 (rev 02)
00:1d.1 USB Controller: Intel Corp. 82801EB/ER (ICH5/ICH5R) USB UHCI #2 (rev 02)
00:1d.2 USB Controller: Intel Corp. 82801EB/ER (ICH5/ICH5R) USB UHCI #3 (rev 02)
00:1d.3 USB Controller: Intel Corp. 82801EB/ER (ICH5/ICH5R) USB UHCI #4 (rev 02)
00:1d.7 USB Controller: Intel Corp. 82801EB/ER (ICH5/ICH5R) USB2 EHCI Controller (rev 02)
00:1e.0 PCI bridge: Intel Corp. 82801BA/CA/DB/EB/ER Hub interface to PCI Bridge (rev c2)
00:1f.0 ISA bridge: Intel Corp. 82801EB/ER (ICH5/ICH5R) LPC Bridge (rev 02)
00:1f.1 IDE interface: Intel Corp. 82801EB/ER (ICH5/ICH5R) Ultra ATA 100 Storage Controller (rev 02)
00:1f.2 IDE interface: Intel Corp. 82801EB (ICH5) Serial ATA 150 Storage Controller (rev 02)
00:1f.3 SMBus: Intel Corp. 82801EB/ER (ICH5/ICH5R) SMBus Controller (rev 02)
00:1f.5 Multimedia audio controller: Intel Corp. 82801EB/ER (ICH5/ICH5R) AC'97 Audio Controller (rev 02)
01:00.0 VGA compatible controller: nVidia Corporation NV17 [GeForce4 MX 440] (rev a3)
02:00.0 SCSI storage controller: Adaptec AHA-2940U/UW/D / AIC-7881U (rev 01)
02:01.0 Ethernet controller: 3Com Corporation 3c905B 100BaseTX [Cyclone] (rev 30)
02:04.0 Class 02b0: Analogic Corp: Unknown device 8004 (rev 07)
02:07.0 FireWire (IEEE 1394): Lucent Microelectronics FW323 (rev 61)
02:08.0 Ethernet controller: Intel Corp. 82562EZ 10/100 Ethernet Controller (rev 01)

proc/interrupts

           CPU0
  0:  507789786    IO-APIC-edge  timer
  1:     459692    IO-APIC-edge  i8042
  7:          0    IO-APIC-edge  parport0
  8:          1    IO-APIC-edge  rtc
  9:          0   IO-APIC-level  acpi
 12:         66    IO-APIC-edge  i8042
 14:     381384    IO-APIC-edge  ide0
 16:          0   IO-APIC-level  uhci_hcd, uhci_hcd
 17:          0   IO-APIC-level  Intel ICH5
 18:          0   IO-APIC-level  libata, uhci_hcd
 19:          0   IO-APIC-level  uhci_hcd
 20:    5748440   IO-APIC-level  eth0
 21:     278400   IO-APIC-level  aic7xxx
 23:          0   IO-APIC-level  ehci_hcd
NMI:          0 
LOC:  507803974 
ERR:          0
MIS:          0


These are identical machines/motherboards. Anybody have a clue
why full-duplex sucks and mismatching FD/HD actually makes
things faster? Is it possible that full-duplex is actually
half-duplex of something strange like that?


Ethtool statistics:

NIC statistics:
     rx_packets: 1732112
     tx_packets: 3612310
     rx_bytes: 162571267
     tx_bytes: 4119843621
     rx_errors: 1094
     tx_errors: 0
     rx_dropped: 0
     tx_dropped: 0
     multicast: 0
     collisions: 50986
     rx_length_errors: 933
     rx_over_errors: 0
     rx_crc_errors: 84
     rx_frame_errors: 77
     rx_fifo_errors: 0
     rx_missed_errors: 0
     tx_aborted_errors: 0
     tx_carrier_errors: 0
     tx_fifo_errors: 0
     tx_heartbeat_errors: 0
     tx_window_errors: 0
     tx_deferred: 298989
     tx_single_collisions: 34534
     tx_multi_collisions: 6779
     tx_flow_control_pause: 122901
     rx_flow_control_pause: 0
     rx_flow_control_unsupported: 0
     tx_tco_packets: 0
     rx_tco_packets: 0

Cheers,
Dick Johnson
Penguin : Linux version 2.6.10 on an i686 machine (5537.79 BogoMips).
 Notice : All mail here is now cached for review by Dictator Bush.
                 98.36% of all statistics are fiction.
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