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ftp performance issues over WiFi

Jithendran Aravind
Prodigy 145 points
Other Parts Discussed in Thread: WL1271

 

Hi All,

We are using the TI Sitara AM37X Evaluation Module (EVM) Sitara (Win CE 6.0 R3)from Mistral for developing a handheld device

 TI WL1271 module is interfaced to the hardware for WiFi functionality.The performance tests for testing the file transfer functionality for a file download from laptop to EVM shows pathetic performance  .

The throughput is approximately 1-2Mbps .However iperf shows good throughput(18Mbps). Please let me know if anyone has observed this behavior.

The results repeats if tested on a wired network (eth interface of EVM) .Also the same ftp application and test setup works with good throughput on a competitor platform(EVM replaced)

 

Thanks,

Jithendran

 (Device/Laptop connected to AP,FTP server running on laptop)
Client application - Customer supplied Kerberos ftp application
Server application - Customer supplied Warftpd

 

  • 0
    Prodigy 145 points

    Hi All,

    We further Analyzed the sniffer logs from site using Wireshark .its observed that

    1.Retransmission packets and packet duplication

    2. TCP widow full observed in logs which consume the majority time slice.

    Can we infer that the driver source corresponding to the packet receival at SDIO stack is the culprit?

    Does the driver/hardware  has the capability to work in DMA enabled mode?

    Rgds,

    Jithendran

  • 0 in reply to Jithendran Aravind
    TI__Genius 9240 points

    Hi Jithendran,

     

    Basically we are supporting Linux releases and we don’t have much experience with WinCE. However please let me understand the issue as I got a bit confused. I understand that the iPerf works very well and the low throughput is only when working with FTP, in addition when running FTP over Ethernet (where there is no WLAN at all) the low throughput were also seen in FTP application.

     

    From the sniffer analysis you observed lots of logs which capture most of the bandwidth, so do you what the logs are? Are they related to the FTP application? In addition what is the reason to the conclusion that the SDIO stack is the one causing the throughput degradation? Since It also happens with Ethernet were the SDIO is not functional at all.

     

    I hope I understood you correctly, please let me know if I missed it…

     

    As for the DMA, in Linux the SDIO works with DMA but I don’t know about WinCE.  

     

    Regards,

    Eyal

     

  • 0 in reply to Eyal a
    Prodigy 145 points

     

    Hi Eyal,

    Thanks for the response.

    1.Iperf client shows 17-19 Mbps.Howerver this is iperf client ported on Win CE.( http://www.research.rutgers.edu/~ionescu/iperf-wince/).iperf server for Win CE is not readily available.So not sure whether this measures the download performance of files(Sitara EVM configured as client and Laptop as ftp server both connected to AP wireless).

    Sniffer logs were captured at Laptop using Wireshark when the ftp client (in Sitara EVK )downloads a file from ftp server(Laptop). Majority of time being consumed for tcp retransmissions.

     

    2.The power management settings in the driver has been modified as follows.

    Power Mode= POWER_MODE_ACTIVE

    Power Level= AWAKE.

    The ftp download time has improved considerably and start delay was eliminated.However not on par with competitor platform

    Does WL1271 client driver/firmware has known performance issues in power save mode?

    3.Is there any other configuration to be enabled in WL1271 driver to boost the performance.Also please let me know if the DMA is enabled in SDIO/wireless card

     

    4.For the wired interface the throughput is around 4-5 Mbps.

    We tried to  enable DMA for wired interface(smc9118-LAN 9220 on Sitara EVK RevG) in the registry file smc9118.reg

    - RxDMAMode changed to 1

    - TxDMAMode changed to 1

    Driver loads however couldnot acquire IP through DHCP and static.Please let us know if anything else to be done for enabling eth DMA.

    Thanks,

    Jithendran

     

  • 0 in reply to Jithendran Aravind
    TI__Genius 9240 points

    Hi Jithendran,

    Since you run iPerf in mode Client TCP on the Sitara EVM without target on the remote side then the testing is not valid, any way if it was UDP (however based on the link you provided only TCP is working) then it would show how much traffic can the EVM push (upstream).

    However since it is TCP then it looks like invalid test. In addition since when you did FTP download you saw lots of retries then there are 2 options, first is the the environments has lots of other AP and there are lots of packets contention on the air, and second is that you had not calibrated the system to begin with.

    However I am not familiar with the Calibration process on WinCE and I suggest that you consult/develop the Calibration process activation using WinCE.

    As for Power save, in case of working in PS mode then the throughput is Low and it is because the way WiFi works in PS mode. However the default value of PS should be AUTO mode, were in that mode when ever we try to pass high traffic data then the Driver goes to ACTIVE mode automatically as such providing higher throughput. So what was the “Power Mode” before you set it to POWER_MODE_ACTIVE? Was it AUTO or PS? As for DMA in wire mode (Ethernet instead of WLAN), I don’t know how to set the DMA in WinCE so I can not know if RxDMAMode and TxDMAMode are enough.

    Regards,

    Eyal