RTOS/TDA2EVM5777: Tx throughput issue with TI NDK

Prasad Jondhale

Mastermind 27743 points

Part Number: TDA2EVM5777

Tool/software: TI-RTOS

Hello All,

I am running network transmit with TCP/IP on TDA2xx device using TI NDK.\

I am seeing my throughput doesn't cross 16Mbps even though my CPU load is just 7% (Cortex A15 running at 1GHz).

Below is my NDK configuration:

NdkConfigGlobal.lowTaskStackSize = 8192;
NdkConfigGlobal.normTaskStackSize = 8192;
NdkConfigGlobal.highTaskStackSize = 8192;
NdkConfigGlobal.ndkThreadStackSize = 8192;
NdkConfigGlobal.pktSizeFrameBuf = 1536;
NdkConfigGlobal.pktNumFrameBufs = 192*8;
NdkConfigGlobal.memRawPageCount = 16*8;
Tcp.transmitBufSize = 256*1024;
Tcp.receiveBufSize = 256*1024;
Tcp.receiveBufLimit = 256*1024;

Also i am not setting any options for recv and send window size via setsockopt.

over 8 years ago

0 ToddMullanix over 8 years ago

TI__Guru* 96960 points

What NDK version are you using?

What is your test case? Are you running it on an isolated network to rule out other traffic?

Todd

0 Prasad Jondhale over 8 years ago in reply to ToddMullanix

TI__Mastermind 27743 points

Hello Todd,

I am using NDK_2_24_02_31.

My use-case is Capture 1280x720 @30fps -> sent to PC via TCP/IP. I see transmit is not happening real time and lot of frame drops happening.
I have tried running use-case without any other functions running.

0 Steven Connell over 8 years ago

TI__Mastermind 45025 points

Hi Prasad,

How big are the TCP RX buffers on the PC side?

The limitation could be coming from that side. Sorry I didn't get a chance to look at the W/S capture yet.

What does the send() call look like? How much data are you passing to send() in each call?

Steve

0 Prasad Jondhale over 8 years ago in reply to Steven Connell

TI__Mastermind 27743 points

Hello Steve,

PFA code snippet for PC and EVM socket configuration and EVM send function. i am sending one full frame (1.8MB) in send call.

Also attached is wireshark dump

/cfs-file/__key/communityserver-discussions-components-files/791/6663.network_5F00_freeze_5F00_issue_5F00_wiredump.pcapng.gz

/cfs-file/__key/communityserver-discussions-components-files/791/1462.network_5F00_throughput_5F00_issue_5F00_code_5F00_snippets.txt

0 Steven Connell over 8 years ago in reply to Prasad Jondhale

TI__Mastermind 45025 points

Hi Prasad,

Quick question - which IP address is which in the capture?

Thanks,

Steve

0 Steven Connell over 8 years ago in reply to Steven Connell

TI__Mastermind 45025 points

Nevermind, I got it :)

172.24.190.16 = PC
172.24.190.214 = target

0 Steven Connell over 8 years ago in reply to Steven Connell

TI__Mastermind 45025 points

Prasad,

It seems that packets are being dropped somehow.

The NDK obviously thinks that it’s been sent, as the TCP sequence number increases (in NDK -> PC TX packets), reflecting the number of bytes sent to the PC.

But the PC stops ACK’ing new data, stuck on the old, missing packet. The NDK eventually hits the retransmit timer expiration and retransmits (seen in packets just below the screen shot).

Once a retransmit happens, performance drops.

The cycle repeats throughout the capture file.

We need to figure out why packets are being dropped.

Steve

0 Steven Connell over 8 years ago in reply to Steven Connell

TI__Mastermind 45025 points

Can you try enabling Selective Acknowledgement (SACK)?

It's set via socket option IPPROTO_TCP + TCP_SACKPERMITTED. Note you need to do this when the socket is first created.

Pretty sure this is exactly the case shown here (first diagram). SACK should help with this:

packetlife.net/.../

Steve

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RTOS/TDA2EVM5777: Tx throughput issue with TI NDK