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CCS/TMDXIDK5718: Measuring processing time on A15

Intellectual 870 points

koji fukumoto

Replies: 8

Views: 164

Part Number: TMDXIDK5718

Tool/software: Code Composer Studio

I am creating a boot program for MPU (A15) using "TMDXIDK5718".
I want to measure the processing time of a function in a program.

I tried the following code, but the return value of the “clock” function was always “0xFFFFFFFF”.

clock_t start = clock();
func();
clock_t end = clock();

I think I should use the "Performance Monitor Count" register.
But I don't know what code to write.
Could you provide a sample code like the one above?

Thank you.

Guru 393215 points

Biser Gatchev-XID
- Nov 29, 2019 7:05 AM
Hi,

Your query has been assigned to a TI engineer. Please note that feedback may be delayed due to holidays in the USA.

Best Regards

Biser
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Expert 8115 points

Frank Livingston
- Dec 2, 2019 11:55 PM
In reply to Biser Gatchev-XID:
Hi,

For CSL (bare-metal), please see the following files:
- pdk_am57xx_1_0_16/packages/ti/csl/arch/a15/cp15.h : header
- pdk_am57xx_1_0_16/packages/ti/csl/arch/a15/V1/performance_unit.asm : asm source
These functions are provided for PMU: ARM_CCNT_Enable, ARM_CCNT_Reset, ARM_CCNT_Read. I think you would simply call ARM_CCNT_Read() before (start) and after (end) your function call.

Please see this thread for using A15 PMU as a time stamp provider in an RTOS-based application:

https://e2e.ti.com/support/processors/f/791/t/617492?DRA756-A15-example-of-timestamp-provider-in-core-clock-cycles

Regards,
Frank
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Intellectual 870 points

koji fukumoto
- Dec 3, 2019 8:56 AM
In reply to Frank Livingston:
Thank you for your reply.
The following code was able to get a value like processing time.
```
unsigned int start_time, end_time;
ARM_CCNT_Enable();
start_time = ARM_CCNT_Read();
func();
end_time = ARM_CCNT_Read();
```
start_time = 0

end_time = 18052
The result was obtained.

How can I convert this "18052" to milliseconds?

Thank you.
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Expert 8115 points

Frank Livingston
- Dec 3, 2019 4:39 PM
In reply to koji fukumoto:
Hi,

Please see the header in performance_unit.asm:

* The CCNT is divided by 64 (by setting Bit 3 of PMNC to 1)
* CCNT Read returns the clock value divided by 64 cycles.
* To get the actual CPU cycle multiple it with 64

You can confirm the PMU Cycle Counter is configured this way be inspecting the assembly code in performance_unit.asm. To understand the code, please refer to relevant ARM documentation, e.g.
- DDI0438I_cortex_a15_r4p0_trm.pdf: ARM Cortex-A15 MPCore Processor Reference Manual. See Section 11.3, PMU register summary.
- DDI0406C_C_arm_architecture_reference_manual.pdf: ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition. This will provide details concerning the PMCR, PMCNTENSET, and PMCCNTR regiters, as well as details concerning the assembly language instructions.
To get a time in msec.:
- Multiply PMCCNTR "delta" (end-start) value by 64 to obtain CPU cycle count
- Divide CPU cycle count by CPU clock speed. This is the wall-clock time in seconds.
- Convert sec. to msec. by multiplying by 1000.
Regards,
Frank
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Intellectual 870 points

koji fukumoto
- Dec 4, 2019 12:33 AM
In reply to Frank Livingston:
Hi,
Thank you for your reply.

The CPU clock of TMDXIDK5718 is 1.5GHz.
Is the following calculation method correct?
```
unsigned int start_time, end_time;
double procMS;

ARM_CCNT_Enable();
start_time = ARM_CCNT_Read();
func();
end_time = ARM_CCNT_Read();

procMS = (end_time - start_time) * 64.0 / 1610612736.0 * 1000.0;
```
Thank you.
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Frank Livingston
- Dec 4, 2019 3:11 PM
In reply to koji fukumoto:

I would multiply by 1.5e6 rather than 1.5*1024^3.
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Intellectual 870 points

koji fukumoto
- Dec 5, 2019 12:53 AM
In reply to Frank Livingston:

Hi,
Thank you for your reply.

It is confirmation just in case.
Is it “1.5e6” instead of “1.5e9”?
(Is "1,500,000" instead of "1,500,000,000"?)
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Frank Livingston
- Dec 5, 2019 1:42 AM
In reply to koji fukumoto:

Hi,

Yes, it should be 1.5e9 (Giga), not 1.5e6 (Mega).

Regards,
Frank
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