Re: SO_REUSEPORT - can it be done in kernel?

Eric Dumazet
2011-03-01T11:45:15Z

Le mardi 01 mars 2011 à 06:27 -0500, Thomas Graf a écrit :
> On Tue, Mar 01, 2011 at 12:13:04PM +0100, Eric Dumazet wrote:
> > Its a bit strange two cpus spend time in softirq, unless you have two
> > queryperf sources, and a multiqueue NIC, or maybe you use two NICS ?
>
> one NIC, 2 clients (12 instances per client)
>
> [root@hp-bl460cg7-01 ~]# cat /sys/class/net/eth0/queues/rx-0/rps_cpus
> 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000
>
> [root@hp-bl460cg7-01 ~]# netstat -s | grep err
> 1781377 packet receive errors
>
> > Mind use "perf top -C 1" and "perf top -C 11" to check what these cpus
> > do ?
>

Thanks that's really interesting

> --------------------------------------------------------------------------------------------------------------------
> PerfTop: 16198 irqs/sec kernel:99.1% exact: 0.0% [1000Hz cpu-clock-msecs], (all, CPU: 1)
> --------------------------------------------------------------------------------------------------------------------
>
> samples pcnt function DSO
> _______ _____ ___________________________ ___________________________________________________________
>

CPU 1 handles receives from your BENET NIC

(Its a bit strange, given this NIC should provide 4 rx queues). Load
could be split to two cpus in your case (two sources)

Try :

ethtool -S eth0 | grep rx_pk
rxq0: rx_pkts: ??
rxq1: rx_pkts: ??
rxq2: rx_pkts: ??
rxq3: rx_pkts: ??
rxq4: rx_pkts: ??

Its BE_HDR_LEN being 64, small UDP frames are too big to fit in skb
head.

> 51675.00 33.2% _raw_spin_unlock_irqrestore [kernel.kallsyms]
> 12426.00 8.0% clflush_cache_range [kernel.kallsyms]
> 5511.00 3.5% be_poll_rx /lib/modules/2.6.38-rc5+/kernel/drivers/net/benet/be2net.ko
> 4567.00 2.9% __udp4_lib_lookup [kernel.kallsyms]
> 3981.00 2.6% __kmalloc_node_track_caller [kernel.kallsyms]
> 3975.00 2.6% get_rx_page_info /lib/modules/2.6.38-rc5+/kernel/drivers/net/benet/be2net.ko
> 3725.00 2.4% sk_run_filter [kernel.kallsyms]
> 3606.00 2.3% get_page_from_freelist [kernel.kallsyms]
> 3178.00 2.0% __domain_mapping [kernel.kallsyms]
> 3122.00 2.0% kmem_cache_alloc_node [kernel.kallsyms]
> 2839.00 1.8% sock_queue_rcv_skb [kernel.kallsyms]
> 2246.00 1.4% __netif_receive_skb [kernel.kallsyms]
> 2245.00 1.4% nf_iterate [kernel.kallsyms]
> 2081.00 1.3% __udp4_lib_rcv [kernel.kallsyms]
> 2042.00 1.3% ipt_do_table [kernel.kallsyms]
> 1901.00 1.2% _raw_spin_lock [kernel.kallsyms]
> 1856.00 1.2% __alloc_skb [kernel.kallsyms]
> 1645.00 1.1% read_tsc [kernel.kallsyms]
> 1562.00 1.0% nf_ct_tuple_equal [kernel.kallsyms]
> 1562.00 1.0% ip_rcv [kernel.kallsyms]
> 1495.00 1.0% __nf_conntrack_find_get [kernel.kallsyms]
> 1477.00 0.9% sock_def_readable [kernel.kallsyms]
> 1363.00 0.9% find_first_bit [kernel.kallsyms]
> 1360.00 0.9% domain_get_iommu [kernel.kallsyms]
> 1255.00 0.8% udp_queue_rcv_skb [kernel.kallsyms]
> 1174.00 0.8% xfrm4_policy_check.clone.0 [kernel.kallsyms]
> 1138.00 0.7% hash_conntrack_raw [kernel.kallsyms]
> 1000.00 0.6% intel_unmap_page [kernel.kallsyms]
> 959.00 0.6% load_pointer [kernel.kallsyms]
> 957.00 0.6% sock_flag [kernel.kallsyms]
> 938.00 0.6% nf_conntrack_in [kernel.kallsyms]
> 891.00 0.6% _local_bh_enable_ip [kernel.kallsyms]
> 884.00 0.6% eth_type_trans [kernel.kallsyms]
> 832.00 0.5% be_post_rx_frags /lib/modules/2.6.38-rc5+/kernel/drivers/net/benet/be2net.ko
> 829.00 0.5% __alloc_pages_nodemask [kernel.kallsyms]
> 813.00 0.5% kmem_cache_alloc [kernel.kallsyms]
> 802.00 0.5% netif_receive_skb [kernel.kallsyms]
> 802.00 0.5% ip_route_input_common [kernel.kallsyms]
> 723.00 0.5% nf_ct_get_tuple [kernel.kallsyms]
> 720.00 0.5% __intel_map_single [kernel.kallsyms]
> 720.00 0.5% udp_error [kernel.kallsyms]
>
> --------------------------------------------------------------------------------------------------------------------
> PerfTop: 16360 irqs/sec kernel:72.6% exact: 0.0% [1000Hz cpu-clock-msecs], (all, CPU: 11)
> --------------------------------------------------------------------------------------------------------------------
>

CPU 11 handles all TX completions : Its a potential bottleneck.

I might ressurect XPS patch ;)

> samples pcnt function DSO
> _______ _____ _____________________________ ___________________________________________________________
>
> 16993.00 32.4% _raw_spin_unlock_irqrestore [kernel.kallsyms]
> 5833.00 11.1% clflush_cache_range [kernel.kallsyms]
> 3315.00 6.3% be_tx_compl_process /lib/modules/2.6.38-rc5+/kernel/drivers/net/benet/be2net.ko
> 1818.00 3.5% kmem_cache_free [kernel.kallsyms]
> 1415.00 2.7% isc_rwlock_lock /usr/lib64/libisc.so.62.0.1
> 1090.00 2.1% be_poll_tx_mcc /lib/modules/2.6.38-rc5+/kernel/drivers/net/benet/be2net.ko
> 811.00 1.5% skb_release_head_state [kernel.kallsyms]
> 772.00 1.5% skb_release_data [kernel.kallsyms]
> 712.00 1.4% dns_rbt_findnode /usr/lib64/libdns.so.69.0.1
> 703.00 1.3% isc_rwlock_unlock /usr/lib64/libisc.so.62.0.1
> 695.00 1.3% dma_pte_clear_range [kernel.kallsyms]
> 618.00 1.2% kfree_skb [kernel.kallsyms]
> 597.00 1.1% kfree [kernel.kallsyms]
> 553.00 1.1% intel_unmap_page [kernel.kallsyms]
> 531.00 1.0% __do_softirq [kernel.kallsyms]
> 504.00 1.0% isc_stats_increment /usr/lib64/libisc.so.62.0.1
> 397.00 0.8% virt_to_head_page [kernel.kallsyms]
> 306.00 0.6% _raw_spin_lock [kernel.kallsyms]
> 270.00 0.5% domain_get_iommu [kernel.kallsyms]
> 256.00 0.5% dns_name_fullcompare /usr/lib64/libdns.so.69.0.1
> 233.00 0.4% find_first_bit [kernel.kallsyms]
> 222.00 0.4% dns_name_equal /usr/lib64/libdns.so.69.0.1
> 218.00 0.4% __pthread_mutex_lock_internal /lib64/libpthread-2.12.so
> 207.00 0.4% dns_rbtnodechain_init /usr/lib64/libdns.so.69.0.1
> 196.00 0.4% dns_acl_match /usr/lib64/libdns.so.69.0.1
> 194.00 0.4% dma_pte_free_pagetable [kernel.kallsyms]
> 192.00 0.4% dns_name_getlabelsequence /usr/lib64/libdns.so.69.0.1
>