Hi David On Fri, Oct 13, 2017 at 11:56 PM, David Laight <david.lai...@aculab.com> wrote: > From: Traiano Welcome > > (copied to netdev) >> Sent: 13 October 2017 07:16 >> To: linux-s...@vger.kernel.org >> Subject: Kernel Performance Tuning for High Volume SCTP traffic >> >> Hi List >> >> I'm running a linux server processing high volumes of SCTP traffic and >> am seeing large numbers of packet overruns (ifconfig output). > > I'd guess that overruns indicate that the ethernet MAC is failing to > copy the receive frames into kernel memory. > It is probably running out of receive buffers, but might be > suffering from a lack of bus bandwidth. > MAC drivers usually discard receive frames if they can't get > a replacement buffer - so you shouldn't run out of rx buffers. > > This means the errors are probably below SCTP - so changing SCTP parameters > is unlikely to help. >
Does this mean that tuning UDP performance could help ? Or do you mean hardware (NIC) performance could be the issue? > I'd make sure any receive interrupt coalescing/mitigation is turned off. > I'll try that. > David > > >> I think a large amount of performance tuning can probably be done to >> improve the linux kernel's SCTP handling performance, but there seem >> to be no guides on this available. Could anyone advise on this? >> >> >> Here are my current settings, and below, some stats: >> >> >> ----- >> net.sctp.addip_enable = 0 >> net.sctp.addip_noauth_enable = 0 >> net.sctp.addr_scope_policy = 1 >> net.sctp.association_max_retrans = 10 >> net.sctp.auth_enable = 0 >> net.sctp.cookie_hmac_alg = sha1 >> net.sctp.cookie_preserve_enable = 1 >> net.sctp.default_auto_asconf = 0 >> net.sctp.hb_interval = 30000 >> net.sctp.max_autoclose = 8589934 >> net.sctp.max_burst = 40 >> net.sctp.max_init_retransmits = 8 >> net.sctp.path_max_retrans = 5 >> net.sctp.pf_enable = 1 >> net.sctp.pf_retrans = 0 >> net.sctp.prsctp_enable = 1 >> net.sctp.rcvbuf_policy = 0 >> net.sctp.rto_alpha_exp_divisor = 3 >> net.sctp.rto_beta_exp_divisor = 2 >> net.sctp.rto_initial = 3000 >> net.sctp.rto_max = 60000 >> net.sctp.rto_min = 1000 >> net.sctp.rwnd_update_shift = 4 >> net.sctp.sack_timeout = 50 >> net.sctp.sctp_mem = 61733040 82310730 123466080 >> net.sctp.sctp_rmem = 40960 8655000 41943040 >> net.sctp.sctp_wmem = 40960 8655000 41943040 >> net.sctp.sndbuf_policy = 0 >> net.sctp.valid_cookie_life = 60000 >> ----- >> >> >> I'm seeing a high rate of packet errors (almost all overruns) on both >> 10gb NICs attached to my linux server. >> >> The system is handling high volumes of network traffic, so this is >> likely a linux kernel tuning problem. >> >> All the normal tuning parameters I've tried thus far seems to be >> having little effect and I'm still seeing high volumes of packet >> overruns. >> >> Any pointers on other things I could try to get the system handling >> SCTP packets efficiently would be much appreciated! >> >> ----- >> :~# ifconfig ens4f1 >> >> ens4f1 Link encap:Ethernet HWaddr 5c:b9:01:de:0d:4c >> UP BROADCAST RUNNING PROMISC MULTICAST MTU:9000 Metric:1 >> RX packets:22313514162 errors:17598241316 dropped:68 >> overruns:17598241316 frame:0 >> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 >> collisions:0 txqueuelen:1000 >> RX bytes:31767480894219 (31.7 TB) TX bytes:0 (0.0 B) >> Interrupt:17 Memory:c9800000-c9ffffff >> ----- >> >> System details: >> >> OS : Ubuntu Linux (4.11.0-14-generic #20~16.04.1-Ubuntu SMP x86_64 ) >> CPU Cores : 72 >> NIC Model : NetXtreme II BCM57810 10 Gigabit Ethernet >> RAM : 240 GiB >> >> NIC sample stats showing packet error rate: >> >> ---- >> >> for i in `seq 1 10`;do echo "$i) `date`" - $(ifconfig ens4f0| egrep >> "RX"| egrep overruns;sleep 5);done >> >> 1) Thu Oct 12 19:50:40 SGT 2017 - RX packets:8364065830 >> errors:2594507718 dropped:215 overruns:2594507718 frame:0 >> 2) Thu Oct 12 19:50:45 SGT 2017 - RX packets:8365336060 >> errors:2596662672 dropped:215 overruns:2596662672 frame:0 >> 3) Thu Oct 12 19:50:50 SGT 2017 - RX packets:8366602087 >> errors:2598840959 dropped:215 overruns:2598840959 frame:0 >> 4) Thu Oct 12 19:50:55 SGT 2017 - RX packets:8367881271 >> errors:2600989229 dropped:215 overruns:2600989229 frame:0 >> 5) Thu Oct 12 19:51:01 SGT 2017 - RX packets:8369147536 >> errors:2603157030 dropped:215 overruns:2603157030frame:0 >> 6) Thu Oct 12 19:51:06 SGT 2017 - RX packets:8370149567 >> errors:2604904183 dropped:215 overruns:2604904183frame:0 >> 7) Thu Oct 12 19:51:11 SGT 2017 - RX packets:8371298018 >> errors:2607183939 dropped:215 overruns:2607183939frame:0 >> 8) Thu Oct 12 19:51:16 SGT 2017 - RX packets:8372455587 >> errors:2609411186 dropped:215 overruns:2609411186frame:0 >> 9) Thu Oct 12 19:51:21 SGT 2017 - RX packets:8373585102 >> errors:2611680597 dropped:215 overruns:2611680597 frame:0 >> 10) Thu Oct 12 19:51:26 SGT 2017 - RX packets:8374678508 >> errors:2614053000 dropped:215 overruns:2614053000 frame:0 >> >> ---- >> >> However, checking (with tc) shows no ring buffer overruns on NIC: >> >> ---- >> >> tc -s qdisc show dev ens4f0|egrep drop >> >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) >> >> ----- >> >> Checking tcp retransmits, the rate is low: >> >> ----- >> >> for i in `seq 1 10`;do echo "`date`" - $(netstat -s | grep -i >> retransmited;sleep 2);done >> >> Thu Oct 12 20:04:29 SGT 2017 - 10633 segments retransmited >> Thu Oct 12 20:04:31 SGT 2017 - 10634 segments retransmited >> Thu Oct 12 20:04:33 SGT 2017 - 10636 segments retransmited >> Thu Oct 12 20:04:35 SGT 2017 - 10636 segments retransmited >> Thu Oct 12 20:04:37 SGT 2017 - 10638 segments retransmited >> Thu Oct 12 20:04:39 SGT 2017 - 10639 segments retransmited >> Thu Oct 12 20:04:41 SGT 2017 - 10640 segments retransmited >> Thu Oct 12 20:04:43 SGT 2017 - 10640 segments retransmited >> Thu Oct 12 20:04:45 SGT 2017 - 10643 segments retransmited >> >> ------ >> >> What I've tried so far: >> >> - Tuning the NIC parameters (packet coalesce, offloading, upping NIC >> ring buffers etc ...): >> >> ethtool -L ens4f0 combined 30 >> ethtool -K ens4f0 gso on rx on tx on sg on tso on >> ethtool -C ens4f0 rx-usecs 96 >> ethtool -C ens4f0 adaptive-rx on >> ethtool -G ens4f0 rx 4078 tx 4078 >> >> - sysctl tunables for the kernel (mainly increasing kernel tcp buffers): >> >> --- >> >> sysctl -w net.ipv4.tcp_low_latency=1 >> sysctl -w net.ipv4.tcp_max_syn_backlog=16384 >> sysctl -w net.core.optmem_max=20480000 >> sysctl -w net.core.netdev_max_backlog=5000000 >> sysctl -w net.ipv4.tcp_rmem="65536 1747600 83886080" >> sysctl -w net.core.somaxconn=1280 >> sysctl -w kernel.sched_min_granularity_ns=10000000 >> sysctl -w kernel.sched_wakeup_granularity_ns=15000000 >> sysctl -w net.ipv4.tcp_wmem="65536 1747600 83886080" >> sysctl -w net.core.wmem_max=2147483647 >> sysctl -w net.core.wmem_default=2147483647 >> sysctl -w net.core.rmem_max=2147483647 >> sysctl -w net.core.rmem_default=2147483647 >> sysctl -w net.ipv4.tcp_congestion_control=cubic >> sysctl -w net.ipv4.tcp_rmem="163840 3495200 268754560" >> sysctl -w net.ipv4.tcp_wmem="163840 3495200 268754560" >> sysctl -w net.ipv4.udp_rmem_min="163840 3495200 268754560" >> sysctl -w net.ipv4.udp_wmem_min="163840 3495200 268754560" >> sysctl -w net.ipv4.tcp_mem="268754560 268754560 268754560" >> sysctl -w net.ipv4.udp_mem="268754560 268754560 268754560" >> sysctl -w net.ipv4.tcp_mtu_probing=1 >> sysctl -w net.ipv4.tcp_slow_start_after_idle=0 >> >> >> Results after this (apparently not much): >> >> >> ---- >> >> :~# for i in `seq 1 10`;do echo "$i) `date`" - $(ifconfig ens4f1| >> egrep "RX"| egrep overruns;sleep 5);done >> >> 1) Thu Oct 12 20:42:56 SGT 2017 - RX packets:16260617113 >> errors:10964865836 dropped:68 overruns:10964865836 frame:0 >> 2) Thu Oct 12 20:43:01 SGT 2017 - RX packets:16263268608 >> errors:10969589847 dropped:68 overruns:10969589847 frame:0 >> 3) Thu Oct 12 20:43:06 SGT 2017 - RX packets:16265869693 >> errors:10974489639 dropped:68 overruns:10974489639 frame:0 >> 4) Thu Oct 12 20:43:11 SGT 2017 - RX packets:16268487078 >> errors:10979323070 dropped:68 overruns:10979323070 frame:0 >> 5) Thu Oct 12 20:43:16 SGT 2017 - RX packets:16271098501 >> errors:10984193349 dropped:68 overruns:10984193349 frame:0 >> 6) Thu Oct 12 20:43:21 SGT 2017 - RX packets:16273804004 >> errors:10988857622 dropped:68 overruns:10988857622 frame:0 >> 7) Thu Oct 12 20:43:26 SGT 2017 - RX packets:16276493470 >> errors:10993340211 dropped:68 overruns:10993340211 frame:0 >> 8) Thu Oct 12 20:43:31 SGT 2017 - RX packets:16278612090 >> errors:10997152436 dropped:68 overruns:10997152436 frame:0 >> 9) Thu Oct 12 20:43:36 SGT 2017 - RX packets:16281253727 >> errors:11001834579 dropped:68 overruns:11001834579 frame:0 >> 10) Thu Oct 12 20:43:41 SGT 2017 - RX packets:16283972622 >> errors:11006374277 dropped:68 overruns:11006374277 frame:0 >> >> ---- >> >> Freak the CPU for better performance: >> >> cpufreq-set -r -g performance >> >> Results (nothing significant): >> >> ---- >> >> :~# for i in `seq 1 10`;do echo "$i) `date`" - $(ifconfig ens4f1| >> egrep "RX"| egrep overruns;sleep 5);done >> >> 1) Thu Oct 12 21:53:07 SGT 2017 - RX packets:18506492788 >> errors:14622639426 dropped:68 overruns:14622639426 frame:0 >> 2) Thu Oct 12 21:53:12 SGT 2017 - RX packets:18509314581 >> errors:14626750641 dropped:68 overruns:14626750641 frame:0 >> 3) Thu Oct 12 21:53:17 SGT 2017 - RX packets:18511485458 >> errors:14630268859 dropped:68 overruns:14630268859 frame:0 >> 4) Thu Oct 12 21:53:22 SGT 2017 - RX packets:18514223562 >> errors:14634547845 dropped:68 overruns:14634547845 frame:0 >> 5) Thu Oct 12 21:53:27 SGT 2017 - RX packets:18516926578 >> errors:14638745143 dropped:68 overruns:14638745143 frame:0 >> 6) Thu Oct 12 21:53:32 SGT 2017 - RX packets:18519605412 >> errors:14642929021 dropped:68 overruns:14642929021 frame:0 >> 7) Thu Oct 12 21:53:37 SGT 2017 - RX packets:18522523560 >> errors:14647108982 dropped:68 overruns:14647108982 frame:0 >> 8) Thu Oct 12 21:53:42 SGT 2017 - RX packets:18525185869 >> errors:14651577286 dropped:68 overruns:14651577286 frame:0 >> 9) Thu Oct 12 21:53:47 SGT 2017 - RX packets:18527947266 >> errors:14655961847 dropped:68 overruns:14655961847 frame:0 >> 10) Thu Oct 12 21:53:52 SGT 2017 - RX packets:18530703288 >> errors:14659988398 dropped:68 overruns:14659988398 frame:0 >> >> ---- >> >> Results using sar: >> >> ---- >> >> :~# sar -n EDEV 5 3| egrep "(ens4f1|IFACE)" >> >> 11:17:43 PM IFACE rxerr/s txerr/s coll/s rxdrop/s >> txdrop/s txcarr/s rxfram/s rxfifo/s txfifo/s >> 11:17:48 PM ens4f1 360809.40 0.00 0.00 0.00 >> 0.00 0.00 0.00 360809.40 0.00 >> 11:17:53 PM ens4f1 382500.40 0.00 0.00 0.00 >> 0.00 0.00 0.00 382500.40 0.00 >> 11:17:58 PM ens4f1 353717.00 0.00 0.00 0.00 >> 0.00 0.00 0.00 353717.00 0.00 >> Average: ens4f1 365675.60 0.00 0.00 0.00 >> 0.00 0.00 0.00 365675.60 0.00 >> >> ---- >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-sctp" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html
