[Codel] fq_codel_drop vs a udp flood

Dave Taht dave.taht at gmail.com
Tue May 3 14:11:35 EDT 2016

On Tue, May 3, 2016 at 10:54 AM, Eric Dumazet <eric.dumazet at gmail.com> wrote:
> On Tue, 2016-05-03 at 10:37 -0700, Dave Taht wrote:
>> Thus far this batch drop patch is testing out beautifully. Under a
>> 900Mbit flood going into 100Mbit on the pcengines apu2,  cpu usage for
>> ksoftirqd now doesn't crack 10%, where before (under
>> pie,pfifo,fq_codel,cake & the prior fq_codel) it went to 88% and
>> ultimately bad things happened, like losing routability.
>> I've had it running for hours and I hardly notice it's there.
> Excellent, thanks for testing it.

Getting it up to 4 floods with 8k udp fragments each could take it up
to about 20-30% of cpu.

iperf3 -c -u -P 4 -b200Mbit -t 600 &

still, beyond awesome.

>> Performance for the normal cc controlled and/or sparse flows is
>> unaffected, aside from the uncontrolled flows eating their percentage
>> of the link.
>> Nice work. Thx. This should go into -stable.
>> https://patchwork.ozlabs.org/patch/617307/
>> Sigh. The RFC is past last call...
> It is merged :
> https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=9d18562a227874289fda8ca5d117d8f503f1dcca

the ietf approval process is about 17512 hours longer than the netdev
approval process.


Dave Täht
Let's go make home routers and wifi faster! With better software!

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