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Date: Tue, 23 Sep 2014 20:37:03 +0400
From: "Alexander V. Chernikov" <melifaro@FreeBSD.org>
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To: Adrian Chadd <adrian@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>
Subject: Re: How do I balance bandwidth over several virtual NICs?
References: <DUB125-W13FDC584F5DF9881CF5FDEBCB30@phx.gbl>	<CA+P_MZGA_uz_H_QsB+dgXEgbXNCjv7w-OToKby=ww+vKgnU4_Q@mail.gmail.com>	<DUB125-W851F972702452D9809C8E5BCB30@phx.gbl>	<CAJ-Vmo=NGGkOkPWQKZ=3gA3vYYyM2kcjd3m85ymdJY3q4ixxLw@mail.gmail.com>	<5421310C.5010406@FreeBSD.org>	<CAJ-VmomamPVwja2Tgfi46EBu8E5Hohr6FcshsOkDeycEvGV51Q@mail.gmail.com>	<CA+hQ2+hU6XwaeyqdcseL9uusmKfyG4Ko7TwvsZwU=r1cUyCw1w@mail.gmail.com>	<54218EF4.6090102@FreeBSD.org>	<20140923154610.GD84074@onelab2.iet.unipi.it>
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Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>,
 Elof Ofel <elofu17@hotmail.com>
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On 23.09.2014 20:00, Adrian Chadd wrote:
> 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.
Oh, cool.
Yet another reason to turn flow control off by default.
>
>
>
> -a
>