On May 25, 2013, at 1:59 PM, Damien Millescamps <damien.millescamps at 6wind.com> wrote:
> On 05/25/2013 09:23 PM, Damien Millescamps wrote: >> Hi Patrick, >> >> If you are using both ports of the same Niantics at the same time then >> you won't be able to reach the line-rate on both port. > > For a better explanation, you can refer to this post from Alexander > Duyck from Intel on the linux network mailing list: > > http://permalink.gmane.org/gmane.linux.network/207295 > Interesting article. Okay, I attempted to find the bus rate of this card this morning (the output of lspci is below). This shows me I am capable of 5GT/s raw which works out to 4 Gbps/lane with 8 lanes enabled which should, theoretically, give 32 Gbps. Reading the article, the suggestion is that due to the smaller packet the overhead is contributing to more 50% of the PCIe bus traffic. Given that I'm seeing a forwarding speed of only about 12.282 Mpps with ~17% drops for only in one direction (rss enabled, 7 queues enabled with 6 queues used). So the overhead cost is almost 70%? Can this ever do line rate? Under what conditions? It has been my experience that the industry standard is testing throughput using these 64 byte packets. Output of 'lspci -vvv -s 03:00.0': 03:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) Subsystem: Intel Corporation Ethernet Server Adapter X520-2 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2 B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <P ERR- INTx- Latency: 0, Cache Line Size: 64 bytes Interrupt: pin A routed to IRQ 48 Region 0: Memory at d9080000 (64-bit, prefetchable) [size=512K] Region 2: I/O ports at ecc0 [size=32] Region 4: Memory at d91f8000 (64-bit, prefetchable) [size=16K] Capabilities: [40] Power Management version 3 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-) Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=1 PME- Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+ Address: 0000000000000000 Data: 0000 Masking: 00000000 Pending: 00000000 Capabilities: [70] MSI-X: Enable+ Count=64 Masked- Vector table: BAR=4 offset=00000000 PBA: BAR=4 offset=00002000 Capabilities: [a0] Express (v2) Endpoint, MSI 00 DevCap: MaxPayload 512 bytes, PhantFunc 0, Latency L0s <512ns, L1 <64us ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset+ DevCtl: Report errors: Correctable- Non-Fatal+ Fatal+ Unsupported+ RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+ FLReset- MaxPayload 256 bytes, MaxReadReq 512 bytes DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr- TransPend- LnkCap: Port #0, Speed 5GT/s, Width x8, ASPM L0s, Latency L0 <1us, L1 <8us ClockPM- Surprise- LLActRep- BwNot- LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- Retrain- CommClk+ ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed 5GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- DevCap2: Completion Timeout: Range ABCD, TimeoutDis+, LTR-, OBFF Not Supported DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis-, LTR-, OBFF Disabled LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis- Transmit Margin: Normal Operating Range, EnterModifiedCompliance- Complia nceSOS- Compliance De-emphasis: -6dB LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete-, EqualizationPhase 1- EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest- Capabilities: [100 v1] Advanced Error Reporting UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- Un supReq- ACSViol- UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt+ UnxCmplt+ RxOF- MalfTLP- ECRC- Un supReq- ACSViol- UESvrt: DLP+ SDES- TLP+ FCP+ CmpltTO+ CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC+ Un supReq- ACSViol- CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+ CEMsk: RxErr+ BadTLP+ BadDLLP+ Rollover+ Timeout+ NonFatalErr+ AERCap: First Error Pointer: 00, GenCap+ CGenEn- ChkCap+ ChkEn- Capabilities: [140 v1] Device Serial Number 00-1b-21-ff-ff-6b-8d-d4 Capabilities: [150 v1] Alternative Routing-ID Interpretation (ARI) ARICap: MFVC- ACS-, Next Function: 1 ARICtl: MFVC- ACS-, Function Group: 0 Capabilities: [160 v1] Single Root I/O Virtualization (SR-IOV) IOVCap: Migration-, Interrupt Message Number: 000 IOVCtl: Enable- Migration- Interrupt- MSE- ARIHierarchy+ IOVSta: Migration- Initial VFs: 64, Total VFs: 64, Number of VFs: 64, Function Dependency Link: 00 VF offset: 128, stride: 2, Device ID: 10ed Supported Page Size: 00000553, System Page Size: 00000001 Region 0: Memory at 00000000d0000000 (64-bit, non-prefetchable) Region 3: Memory at 00000000d0100000 (64-bit, non-prefetchable) VF Migration: offset: 00000000, BIR: 0 Kernel driver in use: igb_uio Kernel modules: ixgbe Thanks, Patrick > Regards, > -- > Damien Millescamps
