RTOS/EK-TM4C1294XL: Unexpected delay in Http Server using NDK

Ayyappa Swamy Thatavarthy

Prodigy 75 points

Part Number: EK-TM4C1294XL

Tool/software: TI-RTOS

Hi,

I have tried using the http server example downloaded from this wiki page on EK-TM4C1294XL board.

The HTML files are being properly rendered and the CGI functions are being invoked without any issue.

However, the delay for a GET response is around 10-20 ms for initial requests. But, after 10 to 15 continuous calls the delay is peaking to 3000ms for most of the calls thereafter.

I have tested the delay using a REST client (Postman).

And after the http server is standby for about 20 minutes, I am not getting any response and had to reset the board.

I have tried this without any modifications to the code in the example.

Please help resolve the issue.

Thanks,

Ayyappa

over 6 years ago

0 ToddMullanix over 6 years ago

TI__Guru* 96960 points

I'm not familiar with Postman. Can you use WireShark to narrow down where the delay is?

Todd

0 Ayyappa Swamy Thatavarthy over 6 years ago in reply to ToddMullanix

Prodigy 75 points

Hi Todd,

Thanks for immediate reply,

Here is the wire shark capture when I experience a delay. It is visible that, a re-transmission from the client is happening after the first SYN packet.

The "Time" value for the second packet is 3.008302 (not visible in screen shot).

May I know the reason for the SYN packet to be re-transmitted and the cause of this issue?

0 ToddMullanix over 6 years ago in reply to Ayyappa Swamy Thatavarthy

TI__Guru* 96960 points

Is the target doing anything else?

Can you look the EMAC driver to see if any packets are getting dropped? In the expressions window in CCS, add the following: 'EMACSnow.c'::EMACSnow_private

What are you memory settings from the NDK in the .cfg file? For example, in the TCP Echo, we tried to keep it small so the following was used
Global.pktNumFrameBufs = 10;
Global.memRawPageCount = 6;
Global.ndkThreadStackSize = 1536;
Global.lowTaskStackSize = 1024;
Global.normTaskStackSize = 1024;
Global.highTaskStackSize = 1024;
Tcp.transmitBufSize = 1024;
Tcp.receiveBufSize = 1024;

If pktNumFrameBufs is small (e.g. 10), can you increase the size?

Todd

0 Ayyappa Swamy Thatavarthy over 6 years ago in reply to ToddMullanix

Prodigy 75 points

1. I don't see any packets to be dropped with the expression given.
2. As I have previously mentioned, I did not change any setting in the cfg, and the memory settings are as-is shipped with the TIRTOS httpServer example. And here are the settings FYI:
Global.pktNumFrameBufs = 16;
Global.memRawPageCount = 8;
Global.ndkThreadStackSize = 2048;
Global.lowTaskStackSize = 2048;
Global.normTaskStackSize = 2048;
Global.highTaskStackSize = 2048;
Tcp.transmitBufSize = 2048;
Tcp.receiveBufSize = 2048;

Ayyappa

0 ToddMullanix over 6 years ago in reply to Ayyappa Swamy Thatavarthy

TI__Guru* 96960 points

Can you try increasing pktNumFrameBufs fro 16 to 64?

0 Ayyappa Swamy Thatavarthy over 6 years ago in reply to ToddMullanix

Prodigy 75 points

When I increase pktNumFrameBufs from 16 to 64, the TCP re-transmission (displayed in Wireshark) is occurring more frequently. Earlier, it happened only after 10-12 calls, but now its happening after 6-8 calls.

Ayyappa

0 Ayyappa Swamy Thatavarthy over 6 years ago in reply to Ayyappa Swamy Thatavarthy

Prodigy 75 points

Can you please give any update on how to proceed?

0 ToddMullanix over 6 years ago in reply to Ayyappa Swamy Thatavarthy

TI__Guru* 96960 points

We have not been able to reproduce this. Can you attach a sample project that has the problem (and a way to test it)?

Todd

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RTOS/EK-TM4C1294XL: Unexpected delay in Http Server using NDK