Poor 8139 network card performance when sharing IRQ

From: Ricardo Ferreira (stormlabs@gmx.net)
Date: Sun Sep 30 2001 - 11:05:25 EST

I have a dual p3-1Ghz on a Abit VP6 board. Everything is working well except
the network card. I have some nfs mounts and i'm using 4096 wsize and rsize
for performance. However when eth0 and any other card are sharing an IRQ the
result of a ping to the server with a packetsize of 4096 is this:

$ ping -s 4096 fs
PING loki.internal ( 4096 data bytes
4104 bytes from icmp_seq=0 ttl=255 time=1.6 ms
4104 bytes from icmp_seq=1 ttl=255 time=283.5 ms
4104 bytes from icmp_seq=2 ttl=255 time=755.3 ms
4104 bytes from icmp_seq=3 ttl=255 time=2.1 ms
4104 bytes from icmp_seq=4 ttl=255 time=1.6 ms
4104 bytes from icmp_seq=5 ttl=255 time=2.1 ms
4104 bytes from icmp_seq=6 ttl=255 time=1.8 ms
4104 bytes from icmp_seq=7 ttl=255 time=284.1 ms
4104 bytes from icmp_seq=8 ttl=255 time=2.0 ms
4104 bytes from icmp_seq=9 ttl=255 time=284.4 ms
4104 bytes from icmp_seq=10 ttl=255 time=2.0 ms
4104 bytes from icmp_seq=11 ttl=255 time=2.2 ms
4104 bytes from icmp_seq=12 ttl=255 time=754.9 ms
4104 bytes from icmp_seq=13 ttl=255 time=283.7 ms
4104 bytes from icmp_seq=14 ttl=255 time=391.9 ms
--- loki.internal ping statistics ---
15 packets transmitted, 15 packets received, 0% packet loss
round-trip min/avg/max = 1.6/203.5/755.3 ms

... but if i remove the other card (in this case a Miro Video TV Card) the
ping times all drop to about 2ms.

Is this drop in performance normal or is it a bug ? As an aside, anything
lower than 1024 packetsize doesn't slowdown.


|"One World, One Web, One Program" - Microsoft Ad||    stormlabs@gmx.net    |
|"Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitler||http://storm.superzip.net|
       --> thor up 2 days | sentinel up 59 days | loki up 59 days <--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

This archive was generated by hypermail 2b29 : Sun Sep 30 2001 - 21:01:12 EST