Split-phase style transactions separate issuing a request and receiving the result of an operation in different threads. We apply this style to system call mechanism so that a system call is split into several threads in order to cut off the mode changes from system call execution inside the kernel. This style of system call mechanism improves throughput, and is also useful in enhancing locality of reference. In this paper, we call this mechanism as Wrapped System Call (WSC) mechanism, and we evaluate the effectiveness of WSC on commodity processors. WSC mechanism can be effective even on commodity platforms which do not have explicit multithread support. We evaluate WSC mechanism based on a performance evaluation model by using a simplified benchmark. We also apply WSC mechanism to variants of cp program to observe the effect on the enhancement of locality of reference. When we apply WSC mechanism to cp program, the combination of our split-phase style system calls and our scheduling mechanism is effective in improving throughput by reducing mode changes and exploiting locality of reference.