Complex sentence: However, the advantage of giant lock is that it is easy to implement, and there is no need to modify many parts of the operating systems, thus giant lock approach is mostly used by operating systems to implement an initial support for SMP.
Split into simpler sentences: However, the advantage of giant lock is that there is no need to modify many parts of the operating systems, thus it is easy to implement. Giant lock approach is mostly used by operating systems to implement an initial support for SMP.