1.5 Caches Matter

1.5 Caches Matter

• To deal with the processor-memory gap, system designers include smaller, faster storage devices called cache memories that serve as temporary staging areas for information that the processor is likely to need in the near future.
• The L1 and L2 caches are implemented with a hardware technology known as static random access memory(SRAM).

 

1.7 The Operating System Manages the Hardware

• The operating system has two primary purpose.
• (1) to protect the hardware from misuse by runaway applications (2) to provide applications with simple and uniform mechanisms for manipulating complicated and often widly different low-level hardware devices.

1.7.1 Processes

• a single CPU can appear to execute multiple procsses concurrently by having the processor switch among them.
• when the operating system decides to transfer control from the current process to some new process, it performs a context switch by saving the context of the current process, restoring the context of the new process, and then passing control to the new process.
• the transition from one process to another is managed by the operating system KERNEL
• KERNEL is not a separate process, instead, it is a collection of code and data structures that the system uses to manage all the processes.

1.7.2 Threads

• in modern systems a process can actually consist of multiple execution units, called THREADS, each running in the context of the process and sharing the same code and global data.

 

1.8 Systems Communicate with Other Systems Using Networks

• when the system copies a sequence of bytes from main memory to the network adapter, the data flow across the network to another machine, instead of, say, to a local dist drive.