Reducing SysLink MessageQ latency

Stanislaw,

I assume you are using SysLink 2.x on ARM and IPC 1.x on DSP?

You are probably dealing with Linux scheduler latencies. A typical Linux configuration is to get as much work done as possible at the expense of responsiveness. You could try adding the Real-Time patch to your Linux kernel. This makes the Linux kernel more responsive to interrupts at the expense of more kernel overhead.

https://rt.wiki.kernel.org/

On OMAP-L138, there are two interrupt lines from DSP to ARM. This allows you to use another messaging system. SysLink ships with an example called umsg which shows how to do this.

syslink/examples/archive/OMAPL138_linux_elf
ex33_umsg - umsg library and Linux driver
ex34_radar - application using umsg

With these two changes, I saw significant improvement. Here are some benchmarks.

Test with 10,000 messages, ARM 300 MHz, DSP 300 MHz

Umsg: ARM to DSP
ARM to DSP avg=0.020 ms
ARM to DSP min=0.016 ms
ARM to DSP max=0.138 ms (jitter: 0.122)

Umsg: DSP to ARM
DSP to ARM avg=0.110 ms
DSP to ARM min=0.058 ms
DSP to ARM max=0.198 ms (jitter: 0.140)

Otherwise, I think you are already doing as much as you can.

~Ramsey