I've already learnt about the Parallel Sum Reduction technique. However, I want to know if it is possible to add up different values from different Threads to a same __global variable like this :
float a = ...; // Assign different a values for each Thread
Gvar[1] += a; // Do the sum simultaneously to the same global variable index
Thanks
For updating the same global memory location from different work-groups you will need to use atomic functions.
You can do so from different work-items in the same group, but this is usually a bad idea. It is almost always more efficient to perform reduction in local memory within the group and only update a global memory location once in each work-group.
Note that most atomic functions are not available for floating-point data types, so you will need to either use integer types or an alternative method to solve your problem.
