CCS/TMDXIDK5718: Measuring processing time on A15

koji fukumoto

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.

over 4 years ago

0 Biser Gatchev-XID over 4 years ago

TI__Guru**** 393215 points

Hi,

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

0 Frank Livingston over 4 years ago in reply to Biser Gatchev-XID

TI__Mastermind 28788 points

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

0 koji fukumoto over 4 years ago in reply to Frank Livingston

Intellectual 940 points

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.

0 Frank Livingston over 4 years ago in reply to koji fukumoto

TI__Mastermind 28788 points

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

0 koji fukumoto over 4 years ago in reply to Frank Livingston

Intellectual 940 points

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.

0 Frank Livingston over 4 years ago in reply to koji fukumoto

TI__Mastermind 28788 points

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

0 koji fukumoto over 4 years ago in reply to Frank Livingston

Intellectual 940 points

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"?)

0 Frank Livingston over 4 years ago in reply to koji fukumoto

TI__Mastermind 28788 points

Hi,

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

Regards,
Frank

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CCS/TMDXIDK5718: Measuring processing time on A15