###### tags: `homework` `sysprog2017`
2017q3 Homework1 (phonebook)
===
contributed by <`Jetudie`>

---
題目： [C02: phonebook](https://hackmd.io/s/HJJUmdXsZ)

## 開發環境
列出CPU資訊
`$ lscpu`
(要更詳細了解也可以用 `$ cat /proc/cpuinfo` )

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 60
Model name:            Intel(R) Core(TM) i5-4200M CPU @ 2.50GHz
Stepping:              3
CPU MHz:               799.865
CPU max MHz:           3100.0000
CPU min MHz:           800.0000
BogoMIPS:              4988.06
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3

列出系統相關資訊
`$ uname -a`

Linux michael-Lenovo-IdeaPad-Z510 4.10.0-35-generic #39-Ubuntu SMP Wed Sep 13 07:46:59 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

清空 cache, 檢視一下資源 (只開 terminal 的情況)
`$ echo 1 | sudo tee /proc/sys/vm/drop_caches`
`$ free`

              total        used        free      shared  buff/cache   available
Mem:        8087436      281492     7619884       61484      186060     7543304
Swap:      10000380           0    10000380

---
## 效能
#### 一開始的效能

`$ make plot`

`$ make cache-test`

 Performance counter stats for './phonebook_opt' (100 runs):

            35,407      cache-misses              #   46.277 % of all cache refs      ( +-  0.28% )
            76,511      cache-references                                              ( +-  0.37% )
        88,826,649      instructions              #    1.53  insn per cycle           ( +-  0.00% )
        58,161,375      cycles                                                        ( +-  0.19% )

       0.128115937 seconds time elapsed                                          ( +-  0.72% )

## 參考資料
1. [2016 年春季系統課程 Homework 1 解說
](https://www.youtube.com/watch?v=ZICRLKf_bVw)

2. [cache 原理和實驗](https://hackmd.io/s/S14L26-_l)

3. [我的工具筆記](https://hackmd.io/s/SJluWzBhZ)