# Ubuntu 16.04.6 LTS
###### tags: `林納斯`


:::success
:::spoiler 目錄
[TOC]
:::

---

## Problem 1
### Useful Infos
- https://elixir.bootlin.com/linux/v3.10.104/source
- https://chat.openai.com/chat

### Source Code of Interest
- [`struct task_struct`](https://elixir.bootlin.com/linux/v3.10.104/source/include/linux/sched.h#L1041) <small>*（`include/linux/sched.h:1041`）*</small>
- [`struct thread_struct`](https://elixir.bootlin.com/linux/v3.10.104/source/arch/x86/include/asm/processor.h#L442) <small>*（`arch/x86/include/asm/processor.h:442`）*</small>
- [`struct thread_info`](https://elixir.bootlin.com/linux/v3.10.104/source/arch/x86/include/asm/thread_info.h#L25) <small>*（`arch/x86/include/asm/thread_info.h:25`）*</small>
- [`unsigned int task_cpu(...)`](https://elixir.bootlin.com/linux/v3.10.104/source/include/linux/sched.h#L2628) <small>*（`include/linux/sched.h:2628`）*</small>
- [`#define task_thread_info(...)`](https://elixir.bootlin.com/linux/v3.10.104/source/include/linux/sched.h#L2322) <small>*（`include/linux/sched.h:2322`）*</small>
- [`#define smp_processor_id()`](https://elixir.bootlin.com/linux/v3.10.104/source/include/linux/smp.h#L218) <small>*（`include/linux/smp.h:218`）*</small>

### Utilities
- `cat /proc/cpuinfo`
- `lscpu`
- :::spoiler Expert System
:::

### Topics
- Logical & physical CPU ID
- taskset
- current

---

## Problem 2
### Useful Infos
- https://www.maizure.org/projects/evolution_x86_context_switch_linux/
- http://linuxperf.com/?p=209
- https://www.jianshu.com/p/42abcc2c9e50
- https://www.cnblogs.com/long123king/p/3501853.html

### Source Code of Interest
- [`void schedule(void)`](https://elixir.bootlin.com/linux/v3.10.104/source/kernel/sched/core.c#L3052) <small>*（`kernel/sched/core.c:3052`）*</small>
- [`void __schedule(void)`](https://elixir.bootlin.com/linux/v3.10.104/source/kernel/sched/core.c#L2955) <small>*（`kernel/sched/core.c:2955`）*</small>
- [`void context_switch(...)`](https://elixir.bootlin.com/linux/v3.10.104/source/kernel/sched/core.c#L1984) <small>*（`kernel/sched/core.c:1984`）*</small>
- [`#define switch_to(...)`](https://elixir.bootlin.com/linux/v3.10.104/source/arch/x86/include/asm/switch_to.h#L104) <small>*（`arch/x86/include/asm/switch_to.h:104`）*</small>
- ~~[`#define switch_to(...)`](https://elixir.bootlin.com/linux/v3.10.104/source/include/asm-generic/switch_to.h#L25)~~ <small>*（`include/asm-generic/switch_to.h:25`）*</small>
- [`struct task_struct* __switch_to(...)`](https://elixir.bootlin.com/linux/v3.10.104/source/arch/x86/kernel/process_64.c#L272) <small>*（`arch/x86/kernel/process_64.c:272`）*</small>
- [`struct tss_struct`](https://elixir.bootlin.com/linux/v3.10.104/source/arch/x86/include/asm/processor.h#L264) <small>*（`arch/x86/include/asm/processor.h:264`）*</small>
- [`struct x86_hw_tss`](https://elixir.bootlin.com/linux/v3.10.104/source/arch/x86/include/asm/processor.h#L240) <small>*（`arch/x86/include/asm/processor.h:240`）*</small>

### Topics
- `nvcsw` / `nivcsw`
- `sleep` / `usleep` / `nanosleep`
- `sleep_for`
- `gettimeofday`
- task state
- assertion 'sd_id12B_randomize(&id) >= 0' failed at ../src/core/dbus.c:668, function bud_on_connection(). Aborting.
- 
- inline assembly
- cpu-bound / io-bound
- the following makes different results

    std::ios_base::sync_with_stdio(false);
    // std::cin.tie(nullptr);

- ==TODO== analyze the 2 situation in `proj3-iobnd` *(6 situations in total)*:
- print way:
- C `printf`
- C++ `std::cout`
- C++ `std::cout` *(accelerated)*
- with many '\n' or flush
***OR*** stdout to TERMINAL or FILE
- https://stackoverflow.com/questions/1716296/why-does-printf-not-flush-after-the-call-unless-a-newline-is-in-the-format-strin
- https://stackoverflow.com/questions/5229096/does-printf-always-flush-the-buffer-on-encountering-a-newline
- `time ./bin/proj3-iobnd 2> 1.log > 2.log`
vs.
`time ./bin/proj3-iobnd 2> 1.log`
- ==TODO== `strace`
- https://stackoverflow.com/questions/6604007/how-can-i-get-a-list-of-linux-system-calls-and-number-of-args-they-take-automati
- https://github.com/strace/strace/blob/v4.11/linux/x86_64/syscallent.h
- `strace -et=316,317,319 -C ./proj3-cpunum`

#### Schedule
- runqueue
- CFS
- https://hackmd.io/@RinHizakura/S1opp7-mP
- https://hackmd.io/@sysprog/linux-scheduler?type=view#Linux-%E6%A0%B8%E5%BF%83%E8%A8%AD%E8%A8%88-%E4%B8%8D%E5%8F%AA%E6%8C%91%E9%81%B8%E4%BB%BB%E5%8B%99%E7%9A%84%E6%8E%92%E7%A8%8B%E5%99%A8
- https://blog.csdn.net/wukongmingjing/article/details/83106431
- https://liujunming.top/2018/11/20/%E8%BF%9B%E7%A8%8B%E5%88%87%E6%8D%A2switch-to%E5%AE%8F%E7%AC%AC%E4%B8%89%E4%B8%AA%E5%8F%82%E6%95%B0%E5%88%86%E6%9E%90/
- https://man7.org/linux/man-pages/man7/sched.7.html
- https://pinyu.tw/?p=161