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Message-ID: <l2m65634d661004161135h1c1466afi54787022bfc2ce12@mail.gmail.com> Date: Fri, 16 Apr 2010 11:35:36 -0700 From: Tom Herbert <therbert@...gle.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: David Miller <davem@...emloft.net>, netdev@...r.kernel.org Subject: Re: [PATCH v5] rfs: Receive Flow Steering Results with "tbench 16" on an 8 core Intel machine. No RPS/RFS: 2155 MB/sec RPS (0ff mask): 1700 MB/sec RFS: 1097 I am not particularly surprised by the results, using loopback interface already provides good parallelism and RPS/RFS really would only add overhead and more trips between CPUs (last part is why RPS < RFS I suspect)-- I guess this is why we've never enabled RPS on loopback :-) Eric, do you have a particular concern that this could affect a real workload? Tom On Thu, Apr 15, 2010 at 11:56 PM, Eric Dumazet <eric.dumazet@...il.com> wrote: > Le jeudi 15 avril 2010 à 23:33 -0700, David Miller a écrit : >> From: Tom Herbert <therbert@...gle.com> >> Date: Thu, 15 Apr 2010 22:47:08 -0700 (PDT) >> >> > Version 5 of RFS: >> > - Moved rps_sock_flow_sysctl into net/core/sysctl_net_core.c as a >> > static function. >> > - Apply limits to rps_sock_flow_entires systcl and rps_flow_count >> > sysfs variable. >> >> I've read this over a few times and I think it's ready to go into >> net-next-2.6, we can tweak things as-needed from here on out. >> >> Eric, what do you think? > > I read the patch and found no error. > > I booted a test machine and performed some tests > > I am a bit worried of a tbench regression I am looking at right now. > > if RFS disabled , tbench 16 -> 4408.63 MB/sec > > > # grep . /sys/class/net/lo/queues/rx-0/* > /sys/class/net/lo/queues/rx-0/rps_cpus:00000000 > /sys/class/net/lo/queues/rx-0/rps_flow_cnt:8192 > # cat /proc/sys/net/core/rps_sock_flow_entries > 8192 > > > echo ffff >/sys/class/net/lo/queues/rx-0/rps_cpus > > tbench 16 -> 2336.32 MB/sec > > > ----------------------------------------------------------------------------------------------------------------------------------------------------- > PerfTop: 14561 irqs/sec kernel:86.3% [1000Hz cycles], (all, 16 CPUs) > ----------------------------------------------------------------------------------------------------------------------------------------------------- > > samples pcnt function DSO > _______ _____ ______________________________ __________________________________________________________ > > 2664.00 5.1% copy_user_generic_string /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 2323.00 4.4% acpi_os_read_port /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 1641.00 3.1% _raw_spin_lock_irqsave /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 1260.00 2.4% schedule /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 1159.00 2.2% _raw_spin_lock /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 1051.00 2.0% tcp_ack /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 991.00 1.9% tcp_sendmsg /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 922.00 1.8% tcp_recvmsg /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 821.00 1.6% child_run /usr/bin/tbench > 766.00 1.5% all_string_sub /usr/bin/tbench > 630.00 1.2% __switch_to /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 608.00 1.2% __GI_strchr /lib/tls/libc-2.3.4.so > 606.00 1.2% ipt_do_table /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 600.00 1.1% __GI_strstr /lib/tls/libc-2.3.4.so > 556.00 1.1% __netif_receive_skb /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 504.00 1.0% tcp_transmit_skb /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 502.00 1.0% tick_nohz_stop_sched_tick /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 481.00 0.9% _raw_spin_unlock_irqrestore /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 473.00 0.9% next_token /usr/bin/tbench > 449.00 0.9% ip_rcv /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 423.00 0.8% call_function_single_interrupt /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 422.00 0.8% ia32_sysenter_target /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 420.00 0.8% compat_sys_socketcall /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 401.00 0.8% mod_timer /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 400.00 0.8% process_backlog /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 399.00 0.8% ip_queue_xmit /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 387.00 0.7% select_task_rq_fair /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 377.00 0.7% _raw_spin_lock_bh /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > 360.00 0.7% tcp_v4_rcv /lib/modules/2.6.34-rc3-03375-ga4fbf84-dirty/build/vmlinux > > But if RFS is on, why activating rps_cpus change tbench ? > > > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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