Re: Packet time delays on multi-core systems
From: Eric Dumazet <hidden>
Date: 2010-10-01 12:59:35
Also in:
lkml
Le vendredi 01 octobre 2010 à 14:16 +0400, Alexey Vlasov a écrit :
I have also found that: 1. rx overruns is increasing. 2. rx_queue_drop_packet_count is increasing.
So you flood machine with packets, its not an idle one ? I thought you were doing experiments with light trafic.
# ethtool -S eth0 | grep drop
tx_dropped: 0
rx_queue_drop_packet_count: 1260743751
dropped_smbus: 0
rx_queue_0_drops: 0
rx_queue_1_drops: 0
rx_queue_2_drops: 0
rx_queue_3_drops: 0ethtool -S eth0 (full output, not small parts)
quoted hunk ↗ jump to hunk
3. By sending SYN-packets by hping, RST packet doesn't send, but I don't know may be it is just some feature in 2.6.32. newbox # hping -c 1 -S -p 80 111.111.111.111 HPING 111.111.111.111 (eth0 111.111.111.111): S set, 40 headers + 0 data bytes len=46 ip=111.111.111.111 ttl=58 DF id=11471 sport=80 flags=SA seq=0 win=65535 rtt=99.0 ms--- 111.111.111.111 hping statistic ---1 packets tramitted, 1 packets received, 0% packet loss round-trip min/avg/max = 99.0/99.0/99.0 ms 13:59:07.439528 IP newbox.2777 > 111.111.111.111.80: S 345595033:345595033(0) win 512 13:59:07.439626 IP 111.111.111.111.80 > newbox.2777: S 1178827395:1178827395(0) ack 345595034 win 65535 <mss 1460> 13:59:10.439368 IP 111.111.111.111.80 > newbox.2777: S 1178827395:1178827395(0) ack 345595034 win 65535 <mss 1460> 13:59:16.439313 IP 111.111.111.111.80 > newbox.2777: S 1178827395:1178827395(0) ack 345595034 win 65535 <mss 1460> 13:59:28.439206 IP 111.111.111.111.80 > newbox.2777: S 1178827395:1178827395(0) ack 345595034 win 65535 <mss 1460> As a result I got doubles:
Are you playing with trafic shaping ? tc -s -d qdisc
quoted hunk ↗ jump to hunk
DUP! len=46 ip=111.111.111.111 ttl=58 DF id=27454 sport=80 flags=SA seq=0 win=65535 rtt=3137.8 ms Example of another TCP-session from 2.6.28 kernel: oldbox # hping -c 1 -S -p 80 111.111.111.111 HPING 111.111.111.111 (eth0 111.111.111.111): S set, 40 headers + 0 data bytes len=46 ip=111.111.111.111 ttl=58 DF id=53180 sport=80 flags=SA seq=0 win=65535 rtt=2.9 ms--- 111.111.111.111 hping statistic ---1 packets tramitted, 1 packets received, 0% packet loss round-trip min/avg/max = 2.9/2.9/2.9 ms 14:01:45.225136 IP oldbox.2776 > 111.111.111.111.80: S 1983626200:1983626200(0) win 512 14:01:45.225288 IP 111.111.111.111.80 > oldbox.2776: S 3796385036:3796385036(0) ack 1983626201 win 65535 <mss 1460> 14:01:45.227990 IP oldbox.2776 > 111.111.111.111.80: R 1983626201:1983626201(0) win 0