Diagnosing Slow Network

Diagnosing Slow Network

Post by Dr Nancy's Sweeti » Sat, 02 Mar 2002 11:38:30



On a machine running 4.5-RELEASE, and the network was just too
intolerably slow; on a 10baseT LAN, transfer rates averaged 4K/sec.
This seemed consistent with X, FTP, and just about everything else
that used the network.

The network card was swapped with a different one, and now FTP zips
files back and forth at 900K/sec; the machine can easily manage X
sessions across the network.

The old card was seen as rl0; the new card is recognised as ed0.

For me personally, the slow network is no longer a problem; it runs
as fast as anyone could expect.  But the drastic difference in speed
is probably due to a driver bug, or something, and this appears to be
an ideal opportunity to track said bug down.  If I know how to do
that, this would be perfect. 8-)

The web page has a "submit a problem report" link, but it seems
reasonable to have as complete a report as possible.  Can someone with
more clues tell me what tests to set up and run that might provide
usable information?

I'm happy to donate my time and CPU cycles to the collective debugging
effort, but how do I diagnose the problem?


"I use not only all the brains I have, but all I can borrow as well."
                                                   -- Woodrow Wilson

 
 
 

Diagnosing Slow Network

Post by jp » Sat, 02 Mar 2002 12:05:39


On Fri, 01 Mar 2002 02:38:30 GMT,

[snip: ``the network was slow'' until new card]

Quote:> The old card was seen as rl0; the new card is recognised as ed0.

> For me personally, the slow network is no longer a problem; it runs
> as fast as anyone could expect.  But the drastic difference in speed
> is probably due to a driver bug, or something, and this appears to be
> an ideal opportunity to track said bug down.  If I know how to do
> that, this would be perfect. 8-)

It's obvious to me that you haven't read this froup and the rl driver
source[0] recently. We had another discussion on exactly this card a
day or so ago. All comments scream ``realtec cards are totally worthless
for any performance at all''.

NO, it is NOT a driver problem. It is a _hardware_ problem.

[snip]

Quote:> I'm happy to donate my time and CPU cycles to the collective debugging
> effort, but how do I diagnose the problem?

I'm happy you want to help out, don't get me wrong, but in this case,
the hardware isn't worth the effort. Getting a better card (even a $20
card, as long as it isn't realtec, will do!) is _much_ cheaper than
trying to solve some cheap h/w vendor's hardware fsckups in software.

[0] The comments in there are pretty instructive and even clear to read.
    Read the part in /usr/src/sys/pci/if_rl.c that begins with
    <quote>
      The RealTek 8139 PCI NIC redefines the meaning of 'low end.'
    </quote>

--
  j p d (at) d s b (dot) t u d e l f t (dot) n l .

 
 
 

Diagnosing Slow Network

Post by Bill Vermilli » Sat, 02 Mar 2002 12:32:18




Quote:>On a machine running 4.5-RELEASE, and the network was just too
>intolerably slow; on a 10baseT LAN, transfer rates averaged 4K/sec.
>This seemed consistent with X, FTP, and just about everything else
>that used the network.
>The network card was swapped with a different one, and now FTP zips
>files back and forth at 900K/sec; the machine can easily manage X
>sessions across the network.
>The old card was seen as rl0; the new card is recognised as ed0.
>For me personally, the slow network is no longer a problem; it runs
>as fast as anyone could expect.  But the drastic difference in speed
>is probably due to a driver bug, or something, and this appears to be
>an ideal opportunity to track said bug down.  If I know how to do
>that, this would be perfect. 8-)
>The web page has a "submit a problem report" link, but it seems
>reasonable to have as complete a report as possible.  Can someone with
>more clues tell me what tests to set up and run that might provide
>usable information?

You need to submit a report to RealTek and tell them to stop
builidng such poor chips.  From the driver if_rl.c - which
is for the RealTek chip as shown by your rl0 device we
see this:

-------
/*
 * The RealTek 8139 PCI NIC redefines the meaning of 'low end.' This is
 * probably the worst PCI ethernet controller ever made, with the possible
 * exception of the FEAST chip made by SMC. The 8139 supports bus-master
 * DMA, but it has a terrible interface that nullifies any performance
 * gains that bus-master DMA usually offers.
 *

-------
That is just a short excerpt.  Further into the driver it documents
the exact problems in the design of this card.  It is
/usr/src/sys/pci/if_rl.c if you want all the*details.

Quote:>I'm happy to donate my time and CPU cycles to the collective debugging
>effort, but how do I diagnose the problem?

You can't make a bad piece of hardware work well no matter how much
software you throw at it.  You may make it work better but it's not
worth it.
--

 
 
 

Diagnosing Slow Network

Post by Mishk » Sun, 03 Mar 2002 08:53:58



Quote:>On a machine running 4.5-RELEASE, and the network was just too
>intolerably slow; on a 10baseT LAN, transfer rates averaged 4K/sec.
>This seemed consistent with X, FTP, and just about everything else
>that used the network.
>The network card was swapped with a different one, and now FTP zips
>files back and forth at 900K/sec; the machine can easily manage X
>sessions across the network.
>The old card was seen as rl0; the new card is recognised as ed0.
>For me personally, the slow network is no longer a problem; it runs
>as fast as anyone could expect.  But the drastic difference in speed
>is probably due to a driver bug, or something, and this appears to be
>an ideal opportunity to track said bug down.  If I know how to do
>that, this would be perfect. 8-)
>The web page has a "submit a problem report" link, but it seems
>reasonable to have as complete a report as possible.  Can someone with
>more clues tell me what tests to set up and run that might provide
>usable information?
>I'm happy to donate my time and CPU cycles to the collective debugging
>effort, but how do I diagnose the problem?

Please show output of following commands with 'bad' NIC:
netstat -i
ping -c 20 some.local.machine.name.or.ip

Note: if you get more than 97% packets back, just post final banner -
line (--- bla.bla.bla ping statistics ---) and below.

--
BR, Mishka.

 
 
 

Diagnosing Slow Network

Post by Dr Nancy's Sweeti » Mon, 04 Mar 2002 04:10:12


I asked about a problem with a really slow network connection, which
improved drastically when I swapped in a different network card.  I
suggested that some testing might be in order.

"j p d (at) d s b (dot) t u d e l f t (dot) n l" wrote back, directing
me to the source code for the driver.  That was educational, as I've
never wandered into that area of the source tree before.  Bill
Vermillion also quoted some driver source, which was stark in its
assessment of the RealTek 8139 PCI NIC.

Both people took the view that the card wasn't worth the trouble, so I
returned it, explaining to the shop owners that it wasn't up to snuff.
It had come with a computer I bought, and they were happy to exchange
it for another one.  (I've done pretty well with them before; they're
not really BSD-aware, but they're patient about finding hardware I can
work with and swapping parts in and out until we get a match.)


 
 
 

Diagnosing Slow Network

Post by Bill Vermilli » Mon, 04 Mar 2002 05:56:38




Quote:

>I asked about a problem with a really slow network connection, which
>improved drastically when I swapped in a different network card.  I
>suggested that some testing might be in order.
>"j p d (at) d s b (dot) t u d e l f t (dot) n l" wrote back, directing
>me to the source code for the driver.  That was educational, as I've
>never wandered into that area of the source tree before.  Bill
>Vermillion also quoted some driver source, which was stark in its
>assessment of the RealTek 8139 PCI NIC.
>Both people took the view that the card wasn't worth the trouble, so I
>returned it, explaining to the shop owners that it wasn't up to snuff.
>It had come with a computer I bought, and they were happy to exchange
>it for another one.  (I've done pretty well with them before; they're
>not really BSD-aware, but they're patient about finding hardware I can
>work with and swapping parts in and out until we get a match.)

So now the question is this.  What knew card did you get and how
well does it work.

Bill

--

 
 
 

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