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Date: Sun, 9 Oct 2016 19:48:33 +0000 From: "Chopra, Manish" <Manish.Chopra@...ium.com> To: Eric Dumazet <eric.dumazet@...il.com> CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "maorg@...lanox.com" <maorg@...lanox.com>, "tom@...bertland.com" <tom@...bertland.com> Subject: RE: Accelerated receive flow steering (aRFS) for UDP > -----Original Message----- > From: Eric Dumazet [mailto:eric.dumazet@...il.com] > Sent: Sunday, October 09, 2016 10:45 PM > To: Chopra, Manish <Manish.Chopra@...ium.com> > Cc: netdev@...r.kernel.org; maorg@...lanox.com; tom@...bertland.com > Subject: Re: Accelerated receive flow steering (aRFS) for UDP > > On Sat, 2016-10-08 at 12:25 +0000, Chopra, Manish wrote: > > > -----Original Message----- > > > From: Eric Dumazet [mailto:eric.dumazet@...il.com] > > > Sent: Saturday, October 08, 2016 5:08 AM > > > To: Chopra, Manish <Manish.Chopra@...ium.com> > > > Cc: netdev@...r.kernel.org; maorg@...lanox.com; tom@...bertland.com > > > Subject: Re: Accelerated receive flow steering (aRFS) for UDP > > > > > > On Fri, 2016-10-07 at 22:55 +0000, Chopra, Manish wrote: > > > > Hello Folks, > > > > > > > > I am experimenting aRFS with our NIC devices, and for that I have > > > > kernel 4.8.x installed with below config. > > > > > > > > CONFIG_RPS=y > > > > CONFIG_RFS_ACCEL=y > > > > > > > > # cat /proc/cpuinfo | grep processor > > > > processor : 0 > > > > processor : 1 > > > > processor : 2 > > > > processor : 3 > > > > processor : 4 > > > > processor : 5 > > > > processor : 6 > > > > processor : 7 > > > > processor : 8 > > > > processor : 9 > > > > processor : 10 > > > > processor : 11 > > > > processor : 12 > > > > processor : 13 > > > > processor : 14 > > > > processor : 15 > > > > > > > > I configured rps_sock_flow_entries and our NIC rx queues with below > > > > values > > > > > > > > echo 32768 > /proc/sys/net/core/rps_sock_flow_entries > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-0/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-1/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-2/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-3/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-4/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-5/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-6/rps_flow_cnt > > > > echo 4096 > /sys/class/net/p4p1/queues/rx-7/rps_flow_cnt > > > > > > > > echo ffff > /sys/class/net/p4p1/queues/rx-0/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-1/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-2/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-3/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-4/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-5/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-6/rps_cpus > > > > echo ffff > /sys/class/net/p4p1/queues/rx-7/rps_cpus > > > > > > > > Below is IRQ affinity configuration for NIC irqs used. > > > > > > > > # cat /proc/irq/67/smp_affinity_list > > > > 8 > > > > # cat /proc/irq/68/smp_affinity_list > > > > 9 > > > > # cat /proc/irq/69/smp_affinity_list > > > > 10 > > > > # cat /proc/irq/70/smp_affinity_list > > > > 11 > > > > # cat /proc/irq/71/smp_affinity_list > > > > 12 > > > > # cat /proc/irq/72/smp_affinity_list > > > > 13 > > > > # cat /proc/irq/73/smp_affinity_list > > > > 14 > > > > # cat /proc/irq/74/smp_affinity_list > > > > 15 > > > > > > > > Driver has required feature NETIF_F_NTUPLE set, ndo_rx_flow_steer() > > > > registered and I am running UDP multiple connections stream using > > > > netperf to the host where I am experimenting aRFS. > > > > > > > > # netperf -V > > > > Netperf version 2.7.0 > > > > > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 8,8 -- -m 1470 -P > > > > 5001,48512 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 9,9 -- -m 1470 -P > > > > 5001,37990 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 10,10 -- -m 1470 -P > > > > 5001,40302 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 11,11 -- -m 1470 -P > > > > 5001,39071 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 12,12 -- -m 1470 -P > > > > 5001,58994 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 13,13 -- -m 1470 -P > > > > 5001,59884 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 14,14 -- -m 1470 -P > > > > 5001,40282 & > > > > netperf -H 192.168.200.40 -t UDP_STREAM -l 150 -T 15,15 -- -m 1470 -P > > > > 5001,56042 & > > > > > > > > I see that our registered callback for ndo_rx_flow_steer() "NEVER" > > > > gets invoked for UDP packets, with TCP_STREAM I do see it gets > > > > invoked. > > > > But while running UDP_STREAM I see it gets invoked for some of TCP > > > > packets as netperf also uses TCP managed connections while running > > > > UDP_STREAM. > > > > > > > > My initial investigation suspects that while running UDP_STREAM with > > > > netperf, rps_sock_flow_table doesn't get updated, as packets never > > > > reach to the flow of inet_recvmsg() > > > > where it gets updated using sock_rps_record_flow(). Which might be the > > > > reason it never invokes NIC's flow steering handler ? > > > > > > > > Please note that when I run UDP stream using "iperf" - I do see that > > > > our registered callback function for flow steering gets invoked for > > > > "UDP" packets. > > > > I am not sure if I am missing something in configuration or something > > > > else which is I am unware of ? > > > > > > > > I appreciate any help for this. > > > > > > Make sure you use connected UDP flows > > > > > > > > > netperf -t UDP_STREAM ... -- -N -n > > > > > > Otherwise, one UDP socket can be involved in millions of 4-tuples (aka > > > flows) > > > > > > > > > > Hi Eric, I tried with it but it doesn't help with the said issue. I still don't see that > our registered handler for flow steering (ndo_rx_flow_steer()) is getting > > invoked for UDP packets [ip->protocol = IPPROTO_UDP] .All it gets invoked for > TCP packets only [ip->protocol = IPPROTO_TCP] > > > > netperf -H $1 -t UDP_STREAM -l 150 -T 8,8 -- -N -m 1470 -P 5001,48512 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 9,9 -- -N -m 1470 -P 5001,37990 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 10,10 -- -N -m 1470 -P 5001,40302 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 11,11 -- -N -m 1470 -P 5001,39071 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 12,12 -- -N -m 1470 -P 5001,58994 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 13,13 -- -N -m 1470 -P 5001,59884 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 14,14 -- -N -m 1470 -P 5001,40282 & > > netperf -H $1 -t UDP_STREAM -l 150 -T 15,15 -- -N -m 1470 -P 5001,56042 & > > > > Thanks !! > > Please carefully read what I wrote, and carefully read netperf > documentation. > > When you add -n option to netperf, it _will_ use connected UDP sockets > and your problem will vanish. > > You added '-N' only, which is useless for UDP_STREAM. > > It might help for UDP_RR, but not UDP_STREAM. > > > Hi Eric, I used "-n" as well with "-N" but still the problem doesn't go away. This is what I have done - Started "netserver" on local/test setup #netserver Starting netserver with host 'IN(6)ADDR_ANY' port '12865' and family AF_UNSPEC It starts listening on port "12865" From remote setup, started multiple netperf using different ports for data sockets specified using "-P" with "-N" and "-n" options specified as well. netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 8,8 -- -N -n -m 1400 -P 6660,5550 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 9,9 -- -N -n -m 1400 -P 9990,9880 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 10,10 -- -N -n -m 1400 -P 4455,4400 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 11,11 -- -N -n -m 1400 -P 3300,7800 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 12,12 -- -N -n -m 1400 -P 50512,44444 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 13,13 -- -N -n -m 1400 -P 10512,45672 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 14,14 -- -N -n -m 1400 -P 8888,56721 & netperf -H 192.168.200.40 -l 150 -t UDP_STREAM -T 15,15 -- -N -n -m 1400 -P 9300,8899 & When on local/test receiving setup, I dump skb's IP header protocol field in .ndo_rx_flow_steer() handler - it is still always IPPROTO_TCP. Which has destined port 12865. But that handler never receives a SKB whose IP header protocol field is set to IPPROTO_UDP. As suspected, I believe in receive flow, packets always go in the path where it never match any entry in global flow table in get_rps_cpu() function ,possibly due to packets don't get received from the flow of inet_recvmsg() which updates the global flow table ? 3571 /* First check into global flow table if there is a match */ 3572 ident = sock_flow_table->ents[hash & sock_flow_table->mask]; 3573 if ((ident ^ hash) & ~rps_cpu_mask) 3574 goto try_rps; Hence, it never call set_rps_cpu() which internally is supposed to call .ndo_rx_flow_steer() for the SKB's whose flows to be steered. On another side, when I use "Iperf" for sending UDP stream, which I believe receives the packets from the intet_recvmsg() flow and I do see flows getting steered for UDP packets. [Actually seeing SKB's whose IP header protocol set to IPPROTO_UDP arriving in .ndo-rx_flow_steer()]. iperf -s -u iperf -u -c 192.168.200.40 -t 3000 -i 10 -P 8 Thanks, Manish
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