How can a scalable multiprocessor that uses shared memory avoid having an issue with coherence? What are the negative aspects of it?

Multiprocessor systems are advantageous because of the plethora of options they provide their users due to their ability to accommodate a wide range of processing needs. Please explain in a few words how this benefit contributes to the bloated design of the system.

Problems with shared memory coherence in scalable multiprocessors, and how to avoid them. In what ways are these disadvantages manifested?

How can consistency problems be avoided in a scalable multiprocessor that uses shared memory? What are the bad things about it?

How can a scalable multiprocessor that utilizes shared memory avoid coherence issues? What are its bad features?

How can a scalable multiprocessor with shared memory avoid having a coherence problem? What are the drawbacks of this?

Exploring the interplay between different multiprocessor systems might be one technique to classifying them.

How to avoid coherence problems with scalable shared memory multiprocessors? What are the drawbacks?

What challenges must a concurrent multithreading architecture solve for an operating system, and how does it do so?