On Mon, 2016-05-02 at 16:47 +0300, Roman Yeryomin wrote: > So it looks to me that fq_codel is just broken if it needs half of my > resources.
Agreed. When I wrote fq_codel, I was not expecting that one UDP socket could fill fq_codel with packets, since we have standard backpressure. SO_SNDBUF default on UDP does not allow to send more than 256 packets in a qdisc. So when sk_sndbuf limit is hit, sendmsg() either blocks or returns an error (if in non blocking mode) So it looks like someone really tries hard ;) To reproduce the issue I had to change (as root user) echo 1000000 >/proc/sys/net/core/wmem_default _and_ setup fq_codel with a much lower limit than the default 10240 limit tc qdisc replace dev eth0 root fq_codel limit 300 So please try this fix : https://patchwork.ozlabs.org/patch/617307/ _______________________________________________ Codel mailing list Codel@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/codel