脸PE歇菜面

写码面1.TOP K 读文件
follow up是
什么情况会文件读取失败 失败的情况怎么处理
和有大小写， 标点符号怎么办
2.地雷题 蠡口discuss搜索地雷即有
第二天约下一轮

系统面
看了面筋准备了
1. ls -al *.c 时会发生什么 从源码分析：https://sysadvent.blogspot.com/2 ... ls-rabbit-hole.html
2. run process的时候 ctrl c 之后发生了什么？http://docs.linuxtone.org/ebooks/C&CPP/c/ch33s01.html

3.booting an OS详细过程   
The Linux boot process can be broken down in 4 simple stages:
1. BIOS
The BIOS (stands for "Basic Input/Output System") initializes the hardware and makes sure with a Power-on self test (POST) that all the hardware is good to go. The main job of the BIOS is to load up the bootloader.
2. Bootloader
The bootloader loads the kernel into memory and then starts the kernel with a set of kernel parameters. One of the most common bootloaders is GRUB, which is a universal Linux standard.
3. Kernel
When the kernel is loaded, it immediately initializes devices and memory. The main job of the kernel is to load up the init process.
4. Init
Remember the init process is the first process that gets started, init starts and stops essential service process on the system. There are three major implementations of init in Linux distributions. We will go over them briefly and then dive into them in another course.
There it is, the (very) simple explanation of the Linux boot process. We will go into more detail about these stages in the next lessons.

https://leetcode.com/discuss/int ... ogin-prompt-appears

4. cpu load 很高但是 usage 很低怎么troubleshoot

5. 一个vmstat的输出，先逐条解释各个列是干嘛的，然后让推测下这台机子在干嘛
http://nonfunctionaltestingtools ... tput-explained.html

6. 如果你怀疑有一个程序Disk I/O很慢，你会怎么办？

7. 数据库服务器query返回缓慢 怎么确定bottleneck是diskio, fsio, cpu 还是network的问题
看的书上记的例子大纲：
1. Check resource bottleneck, disk, cpu, network, mpstat, iostat
2. Disks error from /proc, 0 —— iostat: utilization and saturation, disk io latency
3. Script to capture timestamp and db  stack traces when deschedule by kernel,  blocking during file system
4. See if high Workload cause this , use iostat measure IOps, random or sequential access. If not load problem, it is disk itself problem
5. Rate of query steady? Maybe FS fragmentation  — check FS utilization, it's 30%, so OK no fragment problem
6. Guess FS cache miss?  —> disk io high
7. Check cache hit rate  if that is high enough comparing to others, higher ratio means better

+看了些systems performance书的1-3，6-10

都没用上 乐透面试
欧洲哥上来先问
1.你会什么
2. 那你随便讲讲OS吧   答:讲kernel怎么运作, syscall过程讲了一下, context switch详细到register
3. 为什么需要kernel和higher privilege?  答: isolation
4.为什么process有自己的virtual addr space? 答: ease to use + isolation （3easypieces上有详细）
5.你怎么设计symlink？猜了

然后他打开coderpad噼里啪啦打了半页C代码问了个问题 麻了确实不会
他说那咱们换个问题 又打了半页形容问题 1个fs的问题 大概是怎么使得usb上的一个文件插到不同的电脑上显示不同的指定的内容
还问了一些问题实在想不起来了

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已挂 祝大家好运

请问楼主可以提示下地雷是什么题吗？多谢～

能详细说说TOP K 读文件吗？是蠡口的题吗？

PE是performance engineer吗?请问楼主是面CEA组吗？