3COM network performance problems with Redhat 5.0

3COM network performance problems with Redhat 5.0

Post by Doug Rother » Fri, 20 Mar 1998 04:00:00



This is a part praise/part slam post,

First the praise:

I pulled Red Hat 5.0 out of the box, and on the first try it installed
just fine
with a 3COM 3C905TX PCI card. During the install I put in the DNS, my IP
address, etc... There is no router for the issolated 100 megabit
Ethernet lab
I am in so left that blank. It came up like a champ and I could lookup
machines
and ping/ftp/telnet with no problems whatsoever.

Now the slam:

I am very, very disappointed with the performance of this driver. Its
not the
card, and I suspect I have something misconfigured in the RedHat setup.
Its
just short of a amazingly slow. On an issolated 100 megabit Ethernet LAN
of
30 or so machines I get these kind of performance numbers FTPing
binaries
from a monster AIX server:

OS/2 4.0: 1760K per second
Win95/NT 4.0: 900-1000K per second
my RedHat Linux 5.0: 19K per second

Yes, you read that right. 1760K per second on OS/2, 19K per second on
Linux.

Now mind you on OS/2 it pretty much locks the box solid and squeezes the
soul
out of the Pentium Pro 200, while it is transfering at 1760K, and
sometimes I
get lower numbers like 1500K or less depending on what other people are
doing.
On Linux all network traffic I can muster corresponds to less than 2% of
CPU,
and the machine is virtually idle. I am multibooting between OS/2 and
Linux on the same box with the same card, on the same port, so there
should
be NO hardware differences. I even checked the hub and the card to make
sure
it was connected to the ethernet at 100 megabit on both OSes.

So I would really like to use Linux as a backup server for the AIX box,
but I
can't justify using something that performs at less than 1/10th (almost
1/100th)
the other operating systems. What am I doing wrong? Is there something I
can
tweak to up the performance of network I/O? As is its not using hardly
any of the
bandwidth that is available.

Any and all help is appreciated,

 
 
 

3COM network performance problems with Redhat 5.0

Post by E.Damaski » Fri, 20 Mar 1998 04:00:00


: Now the slam:

: my RedHat Linux 5.0: 19K per second

: Yes, you read that right. 1760K per second on OS/2, 19K per second on
: Linux.

Hmm, that's odd. I have the same card here and it does 900k/s in
10 mbit setting. I am curious what other devices are installed in
your machine (IRQ problems?). What about pings, how fast are
those? Do you have "Allow large windows" enabled in the kernel?
What about "Collision" indicator?

--
E.Damaskine



 
 
 

3COM network performance problems with Redhat 5.0

Post by Peter Buss » Sat, 21 Mar 1998 04:00:00


: This is a part praise/part slam post,

: Now the slam:

: I am very, very disappointed with the performance of this driver. Its
: not the
: card, and I suspect I have something misconfigured in the RedHat setup.
: Its
: just short of a amazingly slow. On an issolated 100 megabit Ethernet LAN
: of
: 30 or so machines I get these kind of performance numbers FTPing
: binaries
: from a monster AIX server:

The 3Com PCI cards are not really good cards. I put two of them back to back
between two 200MHz Pentium machines and got no more than 750K/s when FTPing
large numbers of big files. Most files did 600-650K/s. Two SMC EtherPower
(a 10Mbps card with the DEC 21041 chipset) cards in the same machine achieved
1.1M/s for almost all but the smallest files. SMC EtherPower II (with a new
SMC Epic 10/100Mbps chipset) did 2.5-3.3M/s. That is all on the same hardware
and using a cross-cable and using FTP. A combination of SMC EtherPower and
3c905 did 1.0-1.1M/s when the SMC was sending and the 3c905 receiving.

BTW, the SMC EP II driver is less than a year old.

I don't know what causes Linux to be so slow compared to OS/2 on the same
hardware. But it might have to do with polling vs. interrupts.

Groetjes,
Peter Busser
--
Contractor/consultant in UNIX, TCP/IP networks, Internet, security and Junior
Sybase DBA
Tel.: +31-24-6450412 (024-6450412 vanuit Nederland)
I'm the operator with my pocket calculator...

 
 
 

3COM network performance problems with Redhat 5.0

Post by James Youngma » Tue, 24 Mar 1998 04:00:00


  Doug> I pulled Red Hat 5.0 out of the box, and on the first try it
  Doug> installed just fine with a 3COM 3C905TX PCI card. During the
  Doug> install I put in the DNS, my IP address, etc... There is no
  Doug> router for the issolated 100 megabit Ethernet lab I am in so
  Doug> left that blank. It came up like a champ and I could lookup
  Doug> machines and ping/ftp/telnet with no problems whatsoever.

  Doug> Now the slam:

  Doug> I am very, very disappointed with the performance of this
  Doug> driver. Its not the card, and I suspect I have something
  Doug> misconfigured in the RedHat setup.  Its just short of a
  Doug> amazingly slow. On an issolated 100 megabit Ethernet LAN of 30
  Doug> or so machines I get these kind of performance numbers FTPing
  Doug> binaries from a monster AIX server:

  Doug> OS/2 4.0: 1760K per second

Not sure that is possible; check the RECEIVE data rate, not the
TRANSMIT rate.

  Doug> Win95/NT 4.0: 900-1000K per second
  Doug> my RedHat Linux 5.0: 19K per second

The driver for this card needs updating; RH ships with the standard
version in the Linux kernel (0.46).  You should upgrade to at least
version 0.49; you get this from the URL mentioned in the source
(/usr/src/linux/drivers/net/3c59x.c).

If you do this, please post updated (ttcp) benchmarks :-)

 
 
 

3COM network performance problems with Redhat 5.0

Post by Eric Lee Gre » Thu, 26 Mar 1998 04:00:00



>OS/2 4.0: 1760K per second
>Win95/NT 4.0: 900-1000K per second
>my RedHat Linux 5.0: 19K per second

Something's wrong. Make sure you don't have an interrupt conflict on the
Red Hat Linux box. One way to tell is if you can transmit faster than
19k per second but can't transmit faster (means your interrupts are
falling into the bit-bucket).

Even with el-cheapo NE2000 cards I can get 500k/second thruput, so I'm pretty
sure it's not Linux (though it could be a driver). Do you have Win95
co-installed on this same hardware? What does Win95 report?

--

Systems Specialist               Educational Administration Solutions
 "We believe Windows 95 is a walking antitrust violation" -- Bryan Sparks