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Date: Tue, 17 Apr 2012 18:46:44 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: Alexander Duyck <alexander.h.duyck@...el.com> Cc: jeffrey.t.kirsher@...el.com, "Skidmore, Donald C" <donald.c.skidmore@...el.com>, Greg Rose <gregory.v.rose@...el.com>, John Fastabend <john.r.fastabend@...el.com>, Jesse Brandeburg <jesse.brandeburg@...el.com>, netdev <netdev@...r.kernel.org> Subject: Re: [BUG] ixgbe: something wrong with queue selection ? On Tue, 2012-04-17 at 09:01 -0700, Alexander Duyck wrote: > On 04/17/2012 02:16 AM, Jeff Kirsher wrote: > > On Tue, 2012-04-17 at 11:06 +0200, Eric Dumazet wrote: > >> Hi guys > >> > >> I have bad feelings with ixgbe and its multiqueue selection. > >> > >> On a quad core machine (Q6600), I get lots of reorderings on a single > >> TCP stream. > >> > >> > >> Apparently packets happily spread on all available queues, instead of a > >> single one. > >> > >> This defeats GRO at receiver and TCP performance is really bad. > >> > >> # ethtool -S eth5|egrep "x_queue_[0123]_packets" ; taskset 1 netperf -H > >> 192.168.99.1 ; ethtool -S eth5|egrep "x_queue_[0123]_packets" > >> tx_queue_0_packets: 24 > >> tx_queue_1_packets: 26 > >> tx_queue_2_packets: 32 > >> tx_queue_3_packets: 16 > >> rx_queue_0_packets: 11 > >> rx_queue_1_packets: 47 > >> rx_queue_2_packets: 27 > >> rx_queue_3_packets: 22 > >> MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to > >> 192.168.99.1 (192.168.99.1) port 0 AF_INET > >> Recv Send Send > >> Socket Socket Message Elapsed > >> Size Size Size Time Throughput > >> bytes bytes bytes secs. 10^6bits/sec > >> > >> 87380 16384 16384 10.00 3866.43 > >> tx_queue_0_packets: 1653201 > >> tx_queue_1_packets: 608000 > >> tx_queue_2_packets: 541382 > >> tx_queue_3_packets: 536543 > >> rx_queue_0_packets: 434703 > >> rx_queue_1_packets: 137444 > >> rx_queue_2_packets: 131023 > >> rx_queue_3_packets: 128407 > >> > >> # ip ro get 192.168.99.1 > >> 192.168.99.1 dev eth5 src 192.168.99.2 > >> cache ipid 0x438b rtt 4ms rttvar 4ms cwnd 57 reordering 127 > >> > >> # lspci -v -s 02:00.0 > >> 02:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit > >> SFI/SFP+ Network Connection (rev 01) > >> Subsystem: Intel Corporation Ethernet Server Adapter X520-2 > >> Flags: bus master, fast devsel, latency 0, IRQ 16 > >> Memory at f1100000 (64-bit, prefetchable) [size=512K] > >> I/O ports at b000 [size=32] > >> Memory at f1200000 (64-bit, prefetchable) [size=16K] > >> Capabilities: [40] Power Management version 3 > >> Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+ > >> Capabilities: [70] MSI-X: Enable+ Count=64 Masked- > >> Capabilities: [a0] Express Endpoint, MSI 00 > >> Capabilities: [100] Advanced Error Reporting > >> Capabilities: [140] Device Serial Number 00-1b-21-ff-ff-4a-fe-54 > >> Capabilities: [150] Alternative Routing-ID Interpretation (ARI) > >> Capabilities: [160] Single Root I/O Virtualization (SR-IOV) > >> Kernel driver in use: ixgbe > >> Kernel modules: ixgbe > >> > >> > > Adding Don Skidmore and Alex Duyck... > This is probably the result of ATR and the load balancer on the system. > What is likely happening is that the netperf process is getting moved > from CPU to CPU, and this is causing the transmit queue to change. Once > this happens the ATR will cause the receive queue to change in order to > follow the transmitting process. > > One thing you might try is using the "-T" option in netperf to see if > the behaviour occurs if the process is bound to a specific CPU. Another > thing you might try would be to disable ATR by enabling ntuple. You > should be able to do that with "ethtool -K eth5 ntuple on". I used taskset 1 netperf, to force netperf running on cpu0. Problem is incoming ACKs seem to be spreaded, so TCP stack might run on all cpus. -- 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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