My setup:
Server in the cellar + GBit switch. Long cable to the roof. GBit switch. I have three computers in the roof. One has only 100MBit ethernet, one laptop with GBit and a new computer.
Ping times from the old 100MBit computer: 0.5ms on average
Ping times from laptop: 0.4ms on average
Ping times from my new computer: 5ms or 30ms or 200ms on average but I often see ping times up to 980ms. In general, the throughput is very unstable.
I replaced the switch in the roof. No change.
I replace the cable which connects the new computer to the roof switch. No change.
I installed a PCI network card with an Intel GBit chip (82541PI) and used that instead of the built in Realtek RTL8111/8168B. No change. Yes, I'm sure that I plugged the cable into the correct port because I now get a different IP address from my DHCP server.
The very same network card worked perfectly find on my old computer using the same operating system (openSUSE 12.1).
ifconfig
says:
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:15679 errors:0 dropped:0 overruns:0 frame:0
TX packets:13077 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 Sendewarteschlangenlänge:1000
ethtool
says:
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
What could be causing this behavior?
[EDIT] I found something interesting:
# cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
0: 178 0 0 0 0 0 0 0 IR-IO-APIC-edge timer
1: 6 0 0 0 0 0 0 0 IR-IO-APIC-edge i8042
8: 1 0 0 0 0 0 0 0 IR-IO-APIC-edge rtc0
9: 0 0 0 0 0 0 0 0 IR-IO-APIC-fasteoi acpi
12: 10 0 0 0 0 0 0 0 IR-IO-APIC-edge i8042
16: 3302428 0 0 0 0 0 0 0 IR-IO-APIC-fasteoi ehci_hcd:usb1, nvidia, mei, eth1
17: 184 0 0 0 0 0 0 0 IR-IO-APIC-fasteoi snd_hda_intel
23: 16721 0 0 0 0 0 0 0 IR-IO-APIC-fasteoi ehci_hcd:usb2
As you can see, interrupt 16 serves one USB port, the graphics card, "mei" (?) and eth1
.
I guess that would explain why it's slow. How do I assign interrupts in 2012?
Best Answer
My mainboard is an ASUS P8Z77-M. The BIOS version was 0802. This bios has a bug: It assigns the same IRQ (16) to all high-throughput devices which can cause all kinds of problems (like freezing the desktop when you copy files to an USB device).
Upgrading to version 1206 improved the situation. The network card now gets its own IRQ and the ping times are now where they should be: