[dpdk-users] Packet losses using DPDK
aber at semihalf.com
Mon May 15 10:25:55 CEST 2017
It might be a silly guess, but do you wait for the links are up and
ready to send/receive packets?
On Fri, May 12, 2017 at 5:45 PM, <dfernandes at toulouse.viveris.com> wrote:
> Hi !
> I am working with MoonGen which is a fully scriptable packet generator build
> on DPDK.
> (→ https://github.com/emmericp/MoonGen)
> The system on which I perform tests has the following characteristics :
> CPU : Intel Core i3-6100 (3.70 GHz, 2 cores, 2 threads/core)
> NIC : X540-AT2 with 2x10Gbe ports
> OS : Linux Ubuntu Server 16.04 (kernel 4.4)
> I coded a MoonGen script which requests DPDK to transmit packets from one
> physical port and to receive them at the second physical port. The 2
> physical ports are directly connected with an RJ-45 cat6 cable.
> The issue is that I perform the same test with exactly the same script and
> the same parameters several times and the results show a random behavior.
> For most of the tests there is no losses but for some of them I observe
> packet losses. The percentage of lost packets is very variable. It happens
> even when the packet rate is very low.
> Some examples of random failed tests :
> # 1,000,000 packets sent (packets size = 124 bytes, rate = 76 Mbps) → 10170
> lost packets
> # 3,000,000 packets sent (packets size = 450 bytes, rate = 460 Mbps) → ALL
> packets lost
> I tested the following system modifications without success :
> # BIOS parameters :
> Hyperthreading : enable (because the machine has only 2 cores)
> Multi-processor : enable
> Virtualization Technology (VTx) : disable
> Virtualization Technology for Directed I/O (VTd) : disable
> Allow PCIe/PCI SERR# Interrupt (=PCIe System Errors) : disable
> NUMA unavailable
> # use of isolcpus in order to isolate the cores which are in charge of
> transmission and reception
> # hugepages size = 1048576 kB
> # size of buffer descriptors : tried with Tx = 512 descriptors and Rx = 128
> descriptors and also with Tx = 4096 descriptors and Rx = 4096 descriptors
> # Tested with 2 different X540-T2 NICs units
> # I tested all with a Dell FC430 which has a CPU Intel Xeon E5-2660 v3 @
> 2.6GHz with 10 Cores and 2threads/Core (tested with and without
> → same results and even worse
> Remark concerning the NIC stats :
> I used the rte_eth_stats struct in order to get more information about
> the losses and I observed that in some cases, when there is packet losses,
> ierrors value is > 0 and also ierrors + imissed + ipackets < opackets. In
> other cases I get ierrors = 0 and imissed + ipackets = opackets which has
> more sense.
> What could be the origin of that erroneous packets counting?
> Do you have any explanation about that behaviour ?
> Thanks in advance.
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