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From: Kyle Larose <eomereadig@gmail.com>
To: Zhihan Jiang <jackcharm233@gmail.com>
Cc: users@dpdk.org
Subject: Re: [dpdk-users] DPDK weird forwarding loss
Date: Tue, 1 Dec 2015 12:55:32 -0500	[thread overview]
Message-ID: <CAMFWN9kX2K0wsuqJf2w7fJEC_QZNVG7cfiUrpKr_HLwvG8GcQw@mail.gmail.com> (raw)
In-Reply-To: <CAFC-b74WJg+gRVNLnvk1CaY=o5yT8LJEv3nsJiD7Z8793zZpTA@mail.gmail.com>

Hi Jack,

On Mon, Nov 30, 2015 at 8:42 PM, Zhihan Jiang <jackcharm233@gmail.com> wrote:
> Hello,
>

> Other settings: intel_iommu=on iommu=pt / blacklist ixgbevf on the host
> machine / pause frame off / pin all the ports to the same NUMA node &
> socket / VM uses CPU on the same NUMA node & socket.
>

> but there is always ~0.5%- 1% packet loss
>
> The command line for l3fwd is:
> ./build/l3fwd -c6 -n4 -w [whitelist devices] --socket-mem=1024,0 -- -p3
> --config "(0,0,1), (1,0,2)"
>


Try isolating the CPUs on your guest and host so that the forwarding
application cannot be preempted by something else.

See the 'isolcpus' kernel boot parameter.

http://www.linuxtopia.org/online_books/linux_kernel/kernel_configuration/re46.html

In my experience, drops that happen at low rates are caused by the
polling thread not being scheduled to receive packets often enough.
This can either be because it was preempted, which isolcpus will fix,
or because it is sleeping. IIRC l3fwd doesn't sleep, which leaves the
first case the only possibility.

Hope that helps,

Kyle

  reply	other threads:[~2015-12-01 17:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-01  1:42 Zhihan Jiang
2015-12-01 17:55 ` Kyle Larose [this message]
2015-12-02  7:50   ` Zhihan Jiang

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