# [2021q1](http://wiki.csie.ncku.edu.tw/linux/schedule) 第 18 週測驗題
###### tags: `linux2021`

:::info
目的: 檢驗學員對 ==[RCU 同步機制](https://hackmd.io/@sysprog/linux-rcu)==, lock-free 程式設計, concurrent linked list, thread-local storage (tls), atomics, SMP 的 [false-sharing](https://en.wikipedia.org/wiki/False_sharing) 的認知
:::

==[作答表單](https://docs.google.com/forms/d/e/1FAIpQLSfJa6Ex5BbcxBpNyPbZK92rmAIGJ3dqdmNibdkGJ5quC_Kmjg/viewform)==

### 測驗 `1`

考慮二種 concurrent linked list 操作手法:
- lock-based
- lock-free

在 AMD Ryzen Threadripper 2990WX 32-Core Processor 上，參考的效能評比:
- [ ] `bench-lock`
* `982500` operations per second
- [ ] `bench-lockfree`
* `10771081` operations per second

原始程式碼:
* [bench.h](https://gist.github.com/jserv/1789389f5bef5ccc37bb136396985ad8)
* [bench.c](https://gist.github.com/jserv/ec8a5c39c668122aa1d7153002a1323a)
* [lock.c](https://gist.github.com/jserv/dfe37e8aa6d21ed44877c7411cb042ac)
* [lockfree.c](https://gist.github.com/jserv/51d483c32b67ec6f85948fa698a0324e) ==不完整==
* [Makefile](https://gist.github.com/jserv/7b1acd1ef6ac3fc02136ded6848982a9)

執行 `make` 可建構出二個執行檔: `bench-lock` 和 `bench-lockfree`

請參照 [lock.c](https://gist.github.com/jserv/dfe37e8aa6d21ed44877c7411cb042ac) 的行為，補完 [lockfree.c](https://gist.github.com/jserv/51d483c32b67ec6f85948fa698a0324e) 程式碼，使得 `bench-lockfree` 執行符合預期，並不該遇到任何 assertion 錯誤。

==作答區==

XXX = ? (第 97 行)
YYY = ? (第 288 行)
ZZZ = ? (第 288 行)
RRR = ? (第 489 行)