性能通常是主观的. About This Book — Welcome to Systems Performance: Enterprise and the Cloud! This book is about the performance of operating systems and of applications from operating system context, and it is written for both enterprise and cloud computing environments. My aim is to help you get the most out of your systems.</br>

Chapter 1, Introduction

• is an introduction to systems performance analysis, summarizing key concepts and providing examples of performance activities.
• Performance engineering should ideally begin before hardware is chosen or software is written.
• Performance Is Subjective

  Chapter 2, Methodology, provides the background for performance analysis and tuning, including terminology, concepts, models, ethodologies for observation and experimentation, capacity planning, analysis, and statistics.

  Chapter 3, Operating Systems, summarizes kernel internals for the performance analyst. This is necessary background for interpretingnd - understanding what the operating system is doing.

  Chapter 4, Observability Tools, introduces the types of system observability tools available, and the interfaces and frameworks upon hich they are built.

  Chapter 5, Applications, discusses application performance topics and observing them from the operating system.

  Chapter 6, CPUs, covers processors, cores, hardware threads, CPU caches, CPU interconnects, and kernel scheduling.

  Chapter 7, Memory, is about virtual memory, paging, swapping, memory architectures, busses, address spaces, and allocators.

  Chapter 8, File Systems, is about file system I/O performance, including the different caches involved.

  Chapter 9, Disks, covers storage devices, disk I/O workloads, storage controllers, RAID, and the kernel I/O subsystem.

  Chapter 10, Network, is about network protocols, sockets, interfaces, and physical connections.

  Chapter 11, Cloud Computing, introduces operating-system- and hardwarebased virtualization methods in common use for cloud computingnd - their performance overhead, isolation, and observability characteristics.

  Chapter 12, Benchmarking, shows how to benchmark accurately, and how to interpret others’ benchmark results. This is a surprisingly ricky topic, and this chapter shows how you can avoid common mistakes and try to make sense of it.

  Chapter 13, Case Study, contains a systems performance case study, showing how a real cloud customer issue was analyzed from beginning to end.