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Date:      Sat, 14 Mar 2015 10:51:39 -0700
From:      Tim Kientzle <tim@kientzle.com>
To:        Brett Wynkoop <freebsd-arm@wynn.com>
Cc:        freebsd-arm <freebsd-arm@freebsd.org>
Subject:   Re: BeagleBone slow inbound net I/O
Message-ID:  <44FB8364-1310-4FBF-BA79-1B8837DE1C79@kientzle.com>
In-Reply-To: <20150314031542.439cdee3@ivory.wynn.com>
References:  <20150311165115.32327c5a@ivory.wynn.com> <89CEBFCA-6B94-4F48-8DFD-790E4667632D@kientzle.com> <20150314031542.439cdee3@ivory.wynn.com>

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> On Mar 14, 2015, at 12:15 AM, Brett Wynkoop <freebsd-arm@wynn.com> =
wrote:
>=20
> [wynkoop@beaglebone ~]$ sysctl dev.cpsw | grep -i error
> dev.cpsw.0.stats.RxCrcErrors: 262
> dev.cpsw.0.stats.RxAlignErrors: 231
> dev.cpsw.0.stats.CarrierSenseErrors: 0
> [wynkoop@beaglebone ~]$=20
>=20
> So we can see climbing errors.  I am not sure how this compares to the
> results of others. The above was during the first few minutes of a
> buildworld from an nfs share.

Your Ethernet hardware is detecting a lot of low-level network
errors, which generally indicates hardware problems in your
network:  a bad cable maybe, or a dying switch or bad power
supply.

In any event, NFS throughput degrades rapidly on a poor
network, so this probably explains your NFS slowness.

There are a lot of error-related counters that aren=E2=80=99t called =
Errors,
by the way.  In particular, the various collision and overrun
counters don=E2=80=99t actually have =E2=80=9CError=E2=80=9D in the =
name.

On my BeagleBones, the only non-zero error counter I generally
see is the RxStartOfFrameOverruns.

Tim




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