CCS UPDATE CAUSED INCREASED CROSS PATH STALLS

***

I was using CCS3.3 6482 simulator, with cgt 6.0.16, bios 5.31, and SR4( 3.3.50), everything went well.

Days ago I updated CCS to cgt 6.0.25, bios 5.33.06,and SR 11(3.3.81.6), and I compiled the same project ,then run it. Somthing surprising is that

I saw the "Cross Path Stalls " in the profile window came to be 3.6%, wheras it was just 0.2% in the version before updating.

I did some test and found that , the SR11 update seems to cause the problem. If I keep SR4(3.3.50), whatever the cgt or bios is, no increasing of cross path stalls could be seen.

About CROSS PATH STALL concerning C64+ SPLOOP, it is said the cgt 6.0.25 or later could be a fix.

My prject is a codec, contains both C files and assembly files .And the expense calculated by clock() in MCPS increased by 0.3MCPS, which is huge to me .

Is the increased cross path stalls caused by the compiled C files?Since the assembly files should not be reprocessed by assembler.

So , why do the updated components seem not so effective to my project, what's the real reason, and WHAT CAN I DO?

Thanks in advance.

over 15 years ago

0 George Mock over 15 years ago

TI__Guru**** 249260 points

I presume that by changing from SR4 to SR11, this means you upgraded your simulator as well. I say this because the simulator could be the cause of the problem. It is possible the older simulator was undercounting the cross path stalls, and the new simulator is giving you a more accurate answer.

Or ... This could be a performance bug in the compiler. If so, it is very likely that 1 or 2 functions are responsible for the sudden increase in cross path stalls. In this case, you need to find those 1 or 2 functions and submit them here for more analysis.

Note the v6.0.x compiler is fairly old. Consider upgrading to v6.1.x, or maybe even v7.0.x. Read this http://processors.wiki.ti.com/index.php/Compiler_Version_Numbers_and_What_They_Mean to get some idea of what changing to those versions may mean. The best way to upgrade is to use Update Advisor within CCS. An altenative is here http://processors.wiki.ti.com/index.php/Compiler_Releases .

Thanks and regards,

-George

0 *** over 15 years ago in reply to George Mock

Prodigy 130 points

Thanks , George.

Do you mean that the simulaor update makes the simulator more accurate but the actual performance remains the same? How to prove that if it's true?

I did not do the test to find the 1 or 2 functions responsible for the sudden stall increase.I will do that.

0 *** over 15 years ago in reply to ***

Prodigy 130 points

George , I'd like to say that your presumption may be right, :). On the updated CCS simulator, I run the .out file biult by the ccs before updating , and the result also showed an increase of 0.3mcps. Then I built a .out file using the updated CCS 3.3 and run it on the old CCS version , no increasing could be seen. Based on what I get from the tests, I think the simulator update caused the statistical difference but It does not mean a degradation of performance.

One more question, if I use EMULATOR (a board) , can I use clock() function to calculate MCPS?The CCS help seems to say that clock() only works with simulator.What can I do if I wanna know the expense of a project on an Emulator?

0 George Mock over 15 years ago in reply to ***

TI__Guru**** 249260 points

More details about clock are here http://processors.wiki.ti.com/index.php/Time_and_clock_RTS_Functions . You might want to copy how this example uses TSCL to count cycles http://processors.wiki.ti.com/index.php/C6000_CGT_Optimization_Lab_-_1 .

Thanks and regards,

-George

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CCS UPDATE CAUSED INCREASED CROSS PATH STALLS