# 2016q3 Homework1 (raytracing)

## Gnu gprof學習
### 練習用phonebook_hash實作分析

Flat profile:

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
 time   seconds   seconds    calls  ms/call  ms/call  name    
 62.72      0.05     0.05                             main
 25.09      0.07     0.02        1    20.07    20.07  free_hash_table
 12.54      0.08     0.01   349903     0.00     0.00  hash2
  0.00      0.08     0.00   349900     0.00     0.00  append
  0.00      0.08     0.00        3     0.00     0.00  findName
  0.00      0.08     0.00        2     0.00     0.00  diff_in_second
  0.00      0.08     0.00        1     0.00     0.00  creatHashTable
^L
                        Call graph


granularity: each sample hit covers 2 byte(s) for 12.46% of 0.08 seconds

index % time    self  children    called     name
                                                 <spontaneous>
[1]    100.0    0.05    0.03                 main [1]
                0.02    0.00       1/1           free_hash_table [2]
                0.00    0.01  349900/349900      append [4]
                0.00    0.00       3/3           findName [5]
                0.00    0.00       2/2           diff_in_second [6]
                0.00    0.00       1/1           creatHashTable [7]
-----------------------------------------------
                0.02    0.00       1/1           main [1]
[2]     25.0    0.02    0.00       1         free_hash_table [2]
-----------------------------------------------
                0.00    0.00       3/349903      findName [5]
                0.01    0.00  349900/349903      append [4]
[3]     12.5    0.01    0.00  349903         hash2 [3]
-----------------------------------------------
                0.00    0.01  349900/349900      main [1]
[4]     12.5    0.00    0.01  349900         append [4]
                0.01    0.00  349900/349903      hash2 [3]
-----------------------------------------------
                0.00    0.00       3/3           main [1]
[5]      0.0    0.00    0.00       3         findName [5]
                0.00    0.00       3/349903      hash2 [3]
-----------------------------------------------
                0.00    0.00       2/2           main [1]
[6]      0.0    0.00    0.00       2         diff_in_second [6]
-----------------------------------------------
                0.00    0.00       1/1           main [1]
[7]      0.0    0.00    0.00       1         creatHashTable [7]
-----------------------------------------------

可以看出來function call集中在append跟hash，
字典檔為349900，hash次數 = append + findName次數

# 參考資料
[A02: raytracing](https://hackmd.io/s/B1W5AWza)
[使用Gnu gprof进行Linux平台下的程序分析(1)](http://os.51cto.com/art/200703/41426.htm)
[GNU gprof](https://sourceware.org/binutils/docs/gprof/)