who is very good at operating systems in theory and understanding please reply me asap

 This are the topics 

1) Process Description and Control 

2) Threads

3) Concurrency: Mutual Exclusion and Synchronization 

4) Concurrency: Deadlock and Starvation 

5) Memory Management

6) Virtual Memory

7) Uniprocessor Scheduling 

8) Multiprocessor and Real-Time Scheduling

9)  I/O Management and Disk Scheduling 

10) File Management