[realtek] 8139too performance - can you shed some light?

[Ben Greear]

"Carlo E. Prelz" wrote:
> 
>         Subject: Re: [realtek] 8139too performance - can you shed some light?
>         Date: Wed, Aug 01, 2001 at 03:00:17PM -0700
> 
> Quoting Ben Greear (greearb@candelatech.com):
> 
> > See if you can tell where the pkts are being dropped, and for what
> > reason.  Take a look at the /proc/net/dev file on all the machines,
> > for instance.  You can also increase the kernel buffers for sockets.  If you do a
> > netstat -an | grep udp, then you can see your current buffer usage,
> > and that may give you some ideas.  Do that many times because the buffers
> > fill and un-fill quickly.  Finally, you can try increasing
> > the driver TX buffers.
> 
> I spent the whole day exploring the problem, and I reached the
> conclusion that the bottleneck is in the processor. I tried the same
> software with a PII-400MHz and it sustained exactly the data rate I
> expected. I trtied to fit the SBC with 256MB of memory, but the
> situation did not get better. Evidently the simple processing power
> that is required to handle sustained 100MBps traffic is too much for a
> Pentium-mmx class cpu running at 233MHz. When given enough processing
> power, the system runs real smooth.

For what it's worth, I see about 20-40% CPU usage improvement when going
from the realtek to the EEPRO NICs.  I'm not sure why, but it is definately
noticable.  That may be a cheaper design modification than re-working
your CPU.  That said, it takes me about 500Mhz of PII to run 80Mbps
bi-directional sustained over a period of time on EEPRO 100Mbps-FD links.

My program isn't the most efficient, but it has been designed with
throughput in mind.  You can do better if you are residing in kernel
space only, too, but that may not be possible w/out major kernel
hacking :)

Ben

> 
> Many thanks for dedicating some time to my problem.
> 
> Happy <fill the blank>
> 
> Carlo
> 
> --
>   *         Se la Strada e la sua Virtu' non fossero state messe da parte,
> * K * Carlo E. Prelz - fluido@fluido.as             che bisogno ci sarebbe
>   *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)
> 
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-- 
Ben Greear <greearb@candelatech.com>          <Ben_Greear@excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear