How to calculate the processing time of a function?

Please search for the Application Report SPRA887. Even though the app report is written for a specific library and not specifically for the DM648, there is an example on page 5 that shows how to use the CSL TIMER module functions to measure the elapsed time of a called function.

Thanks, it's very useful.

Thanks. 

It's exactly what I used. Thanks.  By the way, TSCL stores CPU cycles that has elapsed？  If the CPU is 891MHz, is that means TSCL will be 891,000,000 after 1 second?  For I found it increased too slow.

dou guo said:

It's exactly what I used. Thanks.  By the way, TSCL stores CPU cycles that has elapsed？  If the CPU is 891MHz, is that means TSCL will be 891,000,000 after 1 second?  For I found it increased too slow.

The time stamp counter (TSC) runs at CPU/1 speed.  If it's increasing too slowly then you may have your PLL programmed incorrectly.  How are you measuring the speed it increases?  How much do you think it's off?

in CCS, you can add a breakpoint in the beginning and the end of your function. Then simulate it and profile the cpu clock cycle. you can get the clock cycle count and transform them into time. Possibly it's a approximate result.

dou guo said:

If the CPU is 891MHz, is that means TSCL will be 891,000,000 after 1 second?

After 1 second TSC will be 891,000,000 higher than the previous time you read it. TSC is the concatenation of TSCH and TSCL. When you read TSCL, TSCH is latched to give you the correct high-32 bits of the count so that there is no mismatch when a rollover occurs. Since TSCL is the low 32 bits of TSC, it will rollover every 4.8 seconds at 891 MHz.

In hardware (not simulator), TSC may continue counting even when the DSP is halted by emulation.

What count value did you get that was too slow? And how are you establishing the time between two reads of TSCL?

On this point the easiest way to check the TSC would be to create a 1-second interrupt which reads and stores the TSCH/L values. If using BIOS you could easily create a PRD function to execute once every 1000 ticks (by default a tick is 1ms) and then have the PRD function read both registers. You should be able to see the TSC increment approximately 891,000,000 times between each call of the PRD function.

I check TSCL value using CCS's view-> register function.  I fount that after the program had executed even for several minutes, the TSCL does not rellover and TSCH is always 0. 

I use a  XDS560 PCI emulater to connect DM648 EVM.

I do not use BIOS, so the first one is prefered.  Thank you anyway.

I do not set PLL manually.  I check TSCL value using CCS's view-> register function.  I fount that after the program had executed even for several minutes, the TSCL does not rellover and TSCH is always 0.   Because it's National Holiday, I will not go back to work until Oct. 9,  so I can not check whether PLL is set correctly now.  Anyway, thanks for your advice.

Based on this behavior I would definitely double-check your PLL settings as it sounds like the CPU is not running at full speed. I took Brad's code and added a dummy delay loop:

 // to start the timer you need to do a one-time dummy write
 TSCL=0;

 // Inside your code to be benchmarked do something like this
 Start_time = TSCL;

 // run code to be benchmarked here
 // Dummy loop
 for(counter = 0; counter < 1000; counter++);
 
 Stop_time = TSCL;

 Total_cycles = Stop_time - Start_time;

0 TSCL value: 89103665

1 TSCL value: 178204261

2 TSCL value: 267304859

3 TSCL value: 356405461

4 TSCL value: 445506059

5 TSCL value: 534606661

6 TSCL value: 623707259

7 TSCL value: 712807861

8 TSCL value: 801908459

9 TSCL value: 891009061

10 TSCL value: 980109663

Thanks, Tim. I can not verify your suggestion right now.  If the problem is the PLL setting, how do I set it correctly?  Is that setted in .gel file?  If that, I noticed that when connecting to EVM board, the GEL Output said that "The CPU is 891MHz", is that correct?

Yes, the GEL file should configure the device to operate at 891MHz. If you want to try out the code I sent I can post it up here.

It would be best if you can post it.  I will try it out later.

Thanks a lot.[:)]