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Date: Tue, 23 Sep 2014 09:00:44 -0700
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Subject: Re: How do I balance bandwidth over several virtual NICs?
From: Adrian Chadd <adrian@freebsd.org>
To: Luigi Rizzo <rizzo@iet.unipi.it>
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Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>,
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 "Alexander V. Chernikov" <melifaro@freebsd.org>
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Ah, this behaviour.

It's called DROP_EN on the intel igb / ixgbe hardware. Grep the
drivers for that particular register bit/setting.

Set that bit for an RX queue and it'll instruct the MAC to drop frames
destined if that RX ring is full to it and keep receiving on the other
rings. Otherwise yes, receiving on that ring with the ring full cuases
the MAC to stop receiving on all rings until that ring has free space.

You flip this on with ixgbe and igb by disabling tx/rx flowcontrol
(sysctl dev.ix|igb.X.fc=0) before configuring the interface.



-a