[svlug] Raising network interface started to last too long

Michael Eager eager at eagercon.com
Sun Sep 20 15:03:38 PDT 2015

On 09/20/2015 01:36 PM, Ivan Sergio Borgonovo wrote:
> I've 2 PC that have the same exact mobo, use 2 slightly different SSD, 2
> slightly different CPU, run both Debian sid.
> Once upon a time one was mine, it took 50 seconds to "Raise network
> interface" and I didn't care that much.
> My wife PC died, I bought the second one and gave her my older one.
> Once moved it took less than few seconds to "Raise network interface"
> since I can't even see the message during boot.
> When I first installed my PC it booted even faster. The overall boot
> sequence took around 10 sec (mainly due to faster SSD, EFI boot and
> different partitioning).
> Recently I had to add a serial cable to my PC, I opened the case, added
> the cable, enabled the serial port in the BIOS.
> Now "Raising network interface" takes 50 sec, every time 50 sec.
> Now I'm addicted to nearly instant boot and I'd like to have it back.
> I can't swear I just did that, but well I can't think of any other thing
> I did that could be related.
> Interfaces report no error even after sustained traffic.
> One PC still takes few seconds to raise the network interface, the other
> one 50.
> dmesg report same messages just at different times.
> The only think I can think of is a rage condition that may be triggered
> by just a small difference in event timing that may be caused by even
> small changes in hardware setup... while it may be possible it doesn't
> sound that probable.

There's no rage condition.  Not likely even a race condition.

This sounds like the boot sequence is waiting for some task
to complete.  This task has a 45 second timeout.  When this completes
in a few seconds, your network starts quickly.  When the task doesn't
complete, and times out, your network startup is delayed by whatever
the timeout period is.

There can be situations during network initialization where the
boot sequence waits for an interface to become ready before
continuing.  You should see some kind of message about waiting
for an interface.  That might mean that the timeout is in the
network initialization and is delayed because something is not
configured correctly.

Alternately, the delay may be before the network is initialized.
Look at what is happening before your network starts up.

Michael Eager	 eager at eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077

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