Hi again, I found another regression by commit 56b765b79 (htb: improved accuracy at high rates).
After the commit HTB does not honor network rate limiting below 500kbps. I have found that the bandwidth problem is related to GSO being enabled on the device. To test the situation, I had to use a real NIC (as I were not allowed to disable GSO on dev "lo", test below). Testing with 100kbit/s: ----------------------- A localhost dev "lo" reproducer commands: tc qdisc add dev lo root handle 1: htb default 1 tc class add dev lo parent 1: classid 1:1 htb rate 100kbit netserver netperf -t TCP_STREAM -l 60 -H 127.0.0.1 -- -m 1024 Measuring the qdisc "rate" via: tc -s -d class show dev lo classid 1:1 I know the qdisc "rate" is not not very reliable/accurate, but I do see a large difference (and so do netperf reported throughput). - Kernel 2.6.32-352.el6 gives rate 98752bit - Kernel 3.10.0-rc1 gives rate 390208bit My real-NIC test show: With GSO: rate 153248bit Without GSO: rate 99320bit Now, we just have to figure out why commit 56b765b79e (htb: improved accuracy at high rates) breaks bandwidth shaping at low rate with GSO enabled... -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer Data: real NIC ============== With GSO: rate 153248bit --------- class htb 1:1 root prio 0 quantum 1250 rate 100000bit ceil 100000bit burst 1600b/1 mpu 0b overhead 0b cburst 1600b/1 mpu 0b overhead 0b level 0 Sent 844892 bytes 568 pkt (dropped 0, overlimits 0 requeues 0) rate 153248bit 13pps backlog 0b 7p requeues 0 lended: 87 borrowed: 0 giants: 0 tokens: -847776554 ctokens: -847776554 Without GSO: rate 99320bit ------------ (disabled via: ethtool -K eth63 gso off gro off tso off) class htb 1:1 root prio 0 quantum 1250 rate 100000bit ceil 100000bit burst 1600b/1 mpu 0b overhead 0b cburst 1600b/1 mpu 0b overhead 0b level 0 Sent 1706968 bytes 1164 pkt (dropped 0, overlimits 0 requeues 0) rate 99320bit 8pps backlog 0b 51p requeues 0 lended: 664 borrowed: 0 giants: 0 tokens: -121054491 ctokens: -121054491 _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
