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Cycle Measurement on ARM11platform using RVISS

Vinay Kumar
Note: This was originally posted on 6th August 2012 at http://forums.arm.com

Hi all,


Iam trying to measure the performance cycles for my application on RVISS ARM1176JZF-S platform.


When I measure the cycles it is giving 471977 cycle counts,

But measuring the same application performance on different machine it is giving 423787 cycle counts (lesser than my measurement).

For measuring the performance cycles on my machine, I followed some steps of settings:

MCCFG=1 in default.ami file and given ICACHE_LINES, DCACHE_LINES to 1024.

but sitll Iam getting difference of 48190 cycles, why this difference of cycles is getting in my machine?

Is I need to set more settings other than above?

Please help me in this.


Thanks in advance,
Vinay.
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  • Arm Employee Badge
    Note: This was originally posted on 7th August 2012 at http://forums.arm.com

    Having MCCFG=1 and fast memories won't entirely remove latencies.  You still have the overhead of the bus interface - which is one of the things RVISS models badly.  To get a number that is close to real you'll need to ensure your executing exclusively from cache and/or TCM. 

    Not that this explains why CCNT reports different numbers on different workstations.  Best guess would be a difference in configuration.  When you connect to RVISS it prints a load of config information to the debugger console.  Have you compared these on both machines?
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  • Arm Employee Badge
    Note: This was originally posted on 7th August 2012 at http://forums.arm.com

    Having MCCFG=1 and fast memories won't entirely remove latencies.  You still have the overhead of the bus interface - which is one of the things RVISS models badly.  To get a number that is close to real you'll need to ensure your executing exclusively from cache and/or TCM. 

    Not that this explains why CCNT reports different numbers on different workstations.  Best guess would be a difference in configuration.  When you connect to RVISS it prints a load of config information to the debugger console.  Have you compared these on both machines?
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