Day 2
1、breaking pi‘s world record with google cloud
【concept】
memory wall：
Originally theorized in 1994 by Wulf and McKee, this concept revolves around the idea that computer processing units (CPUs) are advancing at a fast enough pace that will leave memory (RAM) stagnant. This isn’t going to happen immediately, but assuming current trends in CPU and RAM remain the same, we could hit a memory wall sometime in the near future.
Once we reach this so-called memory wall, program/app execution time will depend almost entirely on the speed at which RAM can send data to the CPU.
n1-megamen-96:
96 vCPU, 1.4TB RAM ,单台ECS的配置。那么是否Google cloud的ECS已经突破了物理机限制，实现跨物理机的VM？
查询Google 官网有如下VM机型介绍
| 机器类型 | 内存（每个 vCPU） | vCPU 数量 | 自定义机器类型？ | 持续使用折扣？ | 处理器 |
|---|---|---|---|---|---|
| 通用 | 0.95–6.5 GB | 1–96 | 是 | 是 |
|
| 计算优化 | 4 GB | 4–60 | 否 | 是 |
|
| 内存优化 | 28 GB | 40–416 | 否 | 是 |
|
| 共享核心 | 0.60 GB | 0.2–0.5 | 否 | 否 |
|
目测，这次pi的世界纪录，应该是用了内存优化型的VM，96vCPU，每vCPU可提供28GB内存，