Systems Performance: Enterprise and the Cloud

7. Memory

System main memory stores application and kernel instructions, their working data, and file system caches. In many systems, the secondary storage for this data is the primary storage devices—the disks—which operate orders of magnitude more slowly. Once main memory has filled, the system may begin switching data between main memory and the storage devices. This is a slow process that will often become a system bottleneck, dramatically decreasing performance. The system may also terminate the largest memory-consuming process.

Other performance factors to consider include the CPU expense of allocating and freeing memory, copying memory, and managing memory address space mappings. On multisocket architectures, memory locality can become ...