Hi Peter,

Peter Robinson <[email protected]> writes:

>> I'm having an issue with two different wandboard quad systems; one is
>> running F22, the other is running F23.  When the system is under high
>> network load, specifically high transmit load, after a while the network
>> just gives up.  Technically it's not VERY high load, only about 2MB/s,
>> but it's high transmit load -- high download load seems to be fine as
>> far as I can tell.  I know that "gives up" isn't a very technical term,
>> but I frankly don't know what else to call it.
>
> Rev B or C?

The one I'm working on right now says Rev C1.  I don't know the rev of
the other one -- I'd have to go open it up to see.  I can do that if you
want the answer, but it's actually my production mythtv backend (and
still running F22) so I can't really run a bunch of tests on that.

>> After I do this the system has network again.  However it's quite
>> frustrating that I have to go through all these hoops.  Note that just
>> pulling the network cable by itself does not seem sufficient to reset
>> the network.
>
> what happens if you "rmmod fec; sleep 5; modprobe fec" does that have
> the same effect as all of the above?

Mostly, yes.  I had to run:

  ifconfig eth0 down; rmmod fec; sleep 5; modprove fec

(without the ifconfig down the rmmod didn't work).  But that did bring
it back to life.

I should note that as of about 5:30am I was going to respond to Sean and
say that "the upgrade to 4.4.3-300.fc23.armv7hl fixed it."  However
while it IS better (lasting about 18 hours versus 2-4) , it did
eventually die around 6:30am (when I manually ran a du -sh to see how
much of the backup had completed in 18 hours).  So clearly something
between 4.2.3 and 4.4.3 improved the situation, but didn't completely
correct it.

>> Is this a hardware problem or a software problem (or a combination of
>> the two)?  I've had it happen on this one system three times today; I
>> can definitely reliably repeat it (although it does take a couple hours
>> until it dies).  It's also happened on another system, but I've not seen
>> it happen since I stopped pulling data from it.
>
> If it's the former it should be able to be worked around with the
> later. I've not seen it but then I don't use my WBQ for high load. The
> i.MX6 onboard NICs do have a through put issue in that they can't do
> line speed Gbit, but rather top out around 450mbps (if memory serves)
> but that shouldn't affect stability.

Right now I think I'm CPU bound via encfs running AES so I think it's
fine that I can't hit the full 1Gbps.  However I suspect the current set
of ARM solutions available might not be the right platform for my
backup server.

Although openssl speed on my Wandboard says I should be getting 20MB/s,
I appear to only be getting about 1MB/s.  (My laptop seems to be able to
do about 100MB/s according to openssl -- strangely "openssl engine" does
not report "aesni" on my F23 x86_64 laptop).

> Peter

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       [email protected]                        PGP key available
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