Subject: de0 on 164LX gives poor throughput
To: None <>
From: Paul H. Anderson <>
List: port-alpha
Date: 04/09/1999 12:05:00
Today is yet another day in alpha land when 1+1 doesn't equal 2.

I've got several racks full of 164LX machines running netbsd 1.3I from
19990122 snapshot.

Each machine HW is: alpha 164LX Dec motherboard, 533MHz 21164, de500
10/100, ide boot disk, adaptec 2940UW, 1GB RAM, two 10K rpm drives, serial

UDP from an alpha to other alphas seems ok (NFS to a server gives about
3-4 MB/sec for reading files).

TCP streams via FTP seem FUBAR.  In pretty much any combination that we've
tried, an alpha talking to an alpha gives about 50-100KBytes/second
throughput - about 1/100 of what it should.  Same HW ifconfig'd to 10baseT
gives 1MB/sec, i.e. full 10baseT throughput.

We've switched cables, hubs, etc.  No change.  Hook two machines up via
crossover cable, same result.  Adding a etherexpress card causes the
machine to hang hard, so I'm guessing other drivers are out.

An x86 freebsd machine outside the alpha net can do an ftp to the alphas
at 4-5MB/second (reasonable for the HW involved).  The same x86 when
talking to an alpha on the same 100baseT switch gives 6.5 MB/second.

But, try as we might, we can't make ftp between alphas give more than
about 100KB/sec, which is about 1/100th of the speed it is perhaps capable

Has anyone seen this on alphas or other platforms?  Does anyone have
reasonable suggestions for other things to try?  Mike has been looking at
driver errors, and we seem to be seeing CRC errors on 1 in about every 20
packets.  No clue if this is normal or not.

Am I having problems with full vs half duplex?  How do I check?

All of the machines report:
de0: abnormal interrupt: transmit underflow (raising TX threshold to 96|256)
de0: abnormal interrupt: transmit underflow (raising TX threshold to 128|512)
de0: abnormal interrupt: transmit underflow (raising TX threshold to 160|1024)

somewhere near boot time.  Dunno if this is related or not.

I'm bald from pulling my hair out.  Any advice is useful.


| Paul Anderson           Public Data Queries, Inc.    |
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