Decreasing runs of inner loop in outer loop
When loops are nested, the running time is the amount of time the innermost loop is executed multiplied by the time it takes to execute the body of the loop. In your case, the innermost loop executes $n+n/2+n/4+\dots+1\lt2n$ and we'll assume that computing the $\log$ takes constant time. So the running time is linear in $n$.