Re: 3Com 905C very slow (400Kbps)

On Wed, 4 Jun 2003, Florian Hackenberger wrote:

> I've brought the 3Com card back to the shop since it was expensive and 
> didn't perform that well.
> I'm now testing on the Realtek 8139 Card.

If the CPU/mainboard are the cause of the slow data rate, this will make 
it even slower as the CPU will spend some time taking care of the data 
transfer with RTL8139.

>   eth0:10851530   20130    0    0    0     0          0         0 
> 50981444   51197  377    0    0     1     754          0

Actually more carrier errors than collisions - cable problems or media 
mismatch.

> TCP STREAM TEST to localhost

Well, testing to localhost gives you an indication of the speed of the CPU 
and memory; you need to test it between 2 computers so that their network 
interfaces are used.

>     ide0: BM-DMA at 0xe800-0xe807, BIOS settings: hda:pio, hdb:pio
>     ide1: BM-DMA at 0xe808-0xe80f, BIOS settings: hdc:pio, hdd:pio
> hda: ST340016A, ATA DISK drive

Could you make sure that hda uses DMA mode instead of PIO (using hdparm) ? 
In PIO mode the CPU is doing lots of work talking to the disk which 
severely limits the data rate of the disk. This could explain the very 
slow file transfer that you are seeing. This is the reason why I asked for 
purely network based transfer (ttcp, netperf, etc.) where the disk is not 
involved at all.

> eth0: Setting 100mbps full-duplex based on auto-negotiated partner 
> ability 45e1.

So autonegotiation does happen (if eth0 is the right interface) ! If 
purely network load is still very slow and with errors, I'd suspect the 
network cables.

-- 
Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: [email protected]



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