In the first example, I

In the first example, I suggest you use a restrictive scope {} to ensure the scope of vecAp, vecBp, vecCp is limited the the immediately following for loop. IOW place { before the declaraton of vecAp and place } after the end of the for loop }. Doing this will inform the compiler that the lifetime of vecAp, vecBp, vecCp is limited to this enclosing scope, and thus may provide the compiler better opportunities to registerize these pointers. Note, in your specific test case, you may have wrapped these statements inside the scope of a timming loop, thus enclosing the scope of vecAp, vecBp, vecCp in your test case, but when later you use the enclosed statements, you may have additional code at the same scope level of vecAp, vecBp, vecCp and may potentially reuse these pointers. The reuse of these pointers may in turn cause the compiler to think/assume the pointers have a lifetime that exceeds the processing for loop. And as a consequence of that, generate code that performs the vecAp++ to memory as opposed to register.

If you run several tests, I do not think it material to use critical section and priority bump (unless your runtime per iteration is rather long).

Jim Dempsey