Well, first... it's important to note that the TC233 only has one core. If you need three cores, consider the TC277 or TC297.
Once you have a CPU with three cores, the rest is relatively simple - any variables declared within the function will be on each CPU's stack, so no conflicts there.
When you say "uses global variable", what does that mean - who updates the variable?
In general, to avoid problems with global variables and the data cache: put global variables in LMU RAM, and change the value of each CPU's PMA0 register from the default value of 0x300 to 0x100, so that LMU RAM is not cached.
Once you have a CPU with three cores, the rest is relatively simple - any variables declared within the function will be on each CPU's stack, so no conflicts there.
When you say "uses global variable", what does that mean - who updates the variable?
In general, to avoid problems with global variables and the data cache: put global variables in LMU RAM, and change the value of each CPU's PMA0 register from the default value of 0x300 to 0x100, so that LMU RAM is not cached.