L3 cache is a hardware level function so unless the application like memtest86+ tells the cpu not to cache, everything is cached.
There are games that is so memory intensive when it comes to IO/s , that the cache plays a smaller role, like “X4: Foundations“.
/sys/bus/platform/drivers/amd_x3d_vcache/AMDI0101 is a global function. You can use ‘taskset’ to set cpu affinity at launch of application.
This i need to try!