《Systems Performance: Enterprise and the Cloud》读书笔记系列(三) —— 第二章(二)
来源:互联网 发布:中国汽车年度销量数据 编辑:程序博客网 时间:2024/05/16 05:54
1. The notion of known-knowns, known-unknowns and unknown-unknowns is important for the field of performance:
a) Known-knowns: These are things you know;
b) Known-unknowns: These are things you know that you do not know;
c) Unknown-unknowns: These are things you do not know you do not know.
2. Performance metrics are statistics generated by the system, applications or additional tools that measure activity of interest. They are studied for performance analysis or monitoring, either numerically at the command line or graphically using visualization. Common types of performance metrics include IOPS(I/O operations per second), throughput(either operations or volume per second), utilization and latency.
Performance metrics are not free; at some point, CPU cycles must be spent on to gather and store them. This cause overhead, which can negatively affect the performance of the target of measurement. This is called observer effect.
3. Utilization is often used for operating system to describe device usage, such as for the CPU and disk devices. Utilization can be time-based or capacity-based.
(a) Time-based utilization is formally defined in queueing theory: the average amount of time the system or resource was busy along with the ratio U=B/T, where U = utilization, B = total time the system was busy during T, the observation period.
(b) Capacity-based utilization: A system or component (such as a disk drive) is able to deliver a certain amount of throughput. At any level of performance, the system or component is working at some proportion of its capacity. That proportion is called utilization. This defines utilization in terms of capacity instead of time.
0 0
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(三) —— 第二章(二)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(四) —— 第二章(三)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(二) —— 第二章(一)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(五) —— 第二章(四)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(六) —— 第二章(五)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(七) —— 第二章(六)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(八) —— 第二章(七)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(九) —— 第二章(八)
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(一) —— 第一章
- Systems.Performance.Enterprise.and.the.Cloud.2013.10.pdf 英文原版 免费下载
- java performance 读书笔记—— (二)os 性能监测
- java performance读书笔记——(四)jvm performance monitoring
- 《Spring + Cloud微服务实战》读书笔记(二)————Spring Boot
- Finance系列(6)之Remittance and International Payment Systems
- 《The C++ programming language》读书笔记(2)——第二章:C++ 概览
- Enterprise Library Step By Step系列(三):数据访问程序块——入门篇
- Enterprise Library Step By Step系列(三):数据访问程序块——入门篇
- Enterprise Library Step By Step系列(二):配置应用程序块——进阶篇
- CVE-2014-6283: Privilege Escalation Vulnerability and Potential Remote Code Execution in SAP Adaptiv
- HDU 4821 String 解题报告(哈希)
- 【学习4】Cocos2d-x 常用控件之Sprite
- 浅析连续子向量,子数组和(一维,二维)问题
- 背包算法问题
- 《Systems Performance: Enterprise and the Cloud》读书笔记系列(三) —— 第二章(二)
- [android]Mac OS环境下真机调试的环境配置
- Android:ListView常见错位之CheckBox错位
- Flume-ng+Kafka+storm的学习笔记
- UVa 442 Matrix Chain Multiplication(矩阵链乘,模拟栈)
- 你的智商几年级,来体验这款小游戏吧!
- leetcode: Gray Code
- 浅析快速排序
- Timer和TimerTask的使用(一