Gigabit Ethernet - Am I asking my PIII733 for too much?

I can get my Xeon (3.06Ghz) machines to easily transfer data at 995
Mbit/s, which I consider a miracle. I would like my PIII to get at
least near half that. I have a PIII 733 (single CPU) with the
2.4.20-27 kernel, and a 3Com 966B-T card (using the bcm5700 ver. 7
module). I have tried all sorts of combiniations of settings, and
this gets me the best results:

/sbin/sysctl -w net.core.rmem_max=8388608
/sbin/sysctl -w net.core.wmem_max=8388608
/sbin/sysctl -w net.core.rmem_default=65536
/sbin/sysctl -w net.core.wmem_default=65536
/sbin/sysctl -w net.ipv4.tcp_rmem="4096 87380 4194304"
/sbin/sysctl -w net.ipv4.tcp_wmem="4096 65536 4194304"
/sbin/sysctl -w net.core.netdev_max_backlog=30000
/sbin/sysctl -w net.ipv4.route.flush=1

/sbin/ifconfig eth1 txqueuelen 10000
/sbin/ifconfig eth1 mtu 9000

The best I can do with a series of FTPs is about 190Mbit/s. The disks
are raid 5 (hardware, write-back caching) with ext3. I would be happy
with 500Mbit/s - am I asking too much?

Matthew E. Kozloski wrote:
> I can get my Xeon (3.06Ghz) machines to easily transfer data at 995
> Mbit/s, which I consider a miracle. I would like my PIII to get at
> least near half that. I have a PIII 733 (single CPU) with the
> 2.4.20-27 kernel, and a 3Com 966B-T card (using the bcm5700 ver. 7
> module).
>
[snip config]
>
> The best I can do with a series of FTPs is about 190Mbit/s. The disks
> are raid 5 (hardware, write-back caching) with ext3. I would be happy
> with 500Mbit/s - am I asking too much?

Yes you are :-)

I assume your Xeon machine have a 66Mhz or 100Mhz PCI bus (PCI-X), but
your PIII have a standard 33MHz PCI bus. Then 109Mbps is about the max
you can expect.

"Matthew E. Kozloski" schrieb:
>
> I can get my Xeon (3.06Ghz) machines to easily transfer data at 995
> Mbit/s, which I consider a miracle. I would like my PIII to get at
> least near half that.
....
> The best I can do with a series of FTPs is about 190Mbit/s. The disks
> are raid 5 (hardware, write-back caching) with ext3. I would be happy
> with 500Mbit/s - am I asking too much?

have a look at Xosview and you will know.

I get as low as 256KByte/s on an FDDi network between a P133 and a P350.
The P133 is at 100% while the P350 is allmost idle.

G.W.

Start out by using network testing software which *only* tests the
network, and see how much you get. My guess is that you'll get far more
than 190 mbit/second.

steve

"Steve Wolfe" <(E-Mail Removed)> wrote in message news:<bpdkjh$1mr5l5$(E-Mail Removed)>...
> Start out by using network testing software which *only* tests the
> network, and see how much you get. My guess is that you'll get far more
> than 190 mbit/second.
>
> steve


While I do see your point, that would give me a 'false' sense of what
my entire server could produce for throughput. Although I am
interested in the raw speed that the NIC only can produce, I am more
interested in the servers ability to deliver a consistent rate of
transfer (hopefully above 200Mbit).

> While I do see your point, that would give me a 'false' sense of what
> my entire server could produce for throughput. Although I am
> interested in the raw speed that the NIC only can produce, I am more
> interested in the servers ability to deliver a consistent rate of
> transfer (hopefully above 200Mbit).

Well, you can stumble around trying to guess what the problem is, or you
can systematically attack the different possibilities, in order of
likeliness. It's up to you. : )

I'd start by testing the throughput of the network itself. Make sure
that nothing there is a limitation. That alone will narrow down the
possibilities by a huge amount.

Next, does your card support interrupt coalescing? I couldn't find
reference to that card having support, but I could be wrong. Trying to
run gigE adapters on a single-CPU machine without it can swamp the CPU in
interrupts, keeping it from being able to do it's job, whereas your
(assumed dual-CPU) Xeon machines can let one CPU handle the interrupts,
while another still does useful work. However, even without it, I would
still imagine that you'd get more then 200 mbits/second on your machine.

Since you're doing FTP, can your disk system keep up with 100+
megaBYTES/second? Can the disk system at the other end? There are a lot
of factors involved. Getting gigabit speeds at the *application* level
certainly isn't as easy as sticking in a gigE card and adjusting some
kernel parameters. On the other hand, you should still be getting more
than what you are seeing.

steve