[Codel] fq_codel_drop vs a udp flood

Roman Yeryomin leroi.lists at gmail.com
Thu May 5 09:25:52 PDT 2016


On 5 May 2016 at 19:12, Eric Dumazet <eric.dumazet at gmail.com> wrote:
> On Thu, 2016-05-05 at 17:53 +0300, Roman Yeryomin wrote:
>
>>
>> qdisc fq_codel 0: dev eth0 root refcnt 2 limit 1024p flows 1024
>> quantum 1514 target 5.0ms interval 100.0ms ecn
>>  Sent 12306 bytes 128 pkt (dropped 0, overlimits 0 requeues 0)
>>  backlog 0b 0p requeues 0
>>   maxpacket 0 drop_overlimit 0 new_flow_count 0 ecn_mark 0
>>   new_flows_len 0 old_flows_len 0
>
>
> Limit of 1024 packets and 1024 flows is not wise I think.
>
> (If all buckets are in use, each bucket has a virtual queue of 1 packet,
> which is almost the same than having no queue at all)
>
> I suggest to have at least 8 packets per bucket, to let Codel have a
> chance to trigger.
>
> So you could either reduce number of buckets to 128 (if memory is
> tight), or increase limit to 8192.

Will try, but what I've posted is default, I didn't change/configure that.

Regards,
Roman



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