Dreamhost CPU resource report:

The only one php script in the website are simple, only have a header() function in it. But it cause a lot of cpu resource:

[razzle]$ more /home/8ta/logs/resources/8ta.sa.analyzed.1
Process               CPU seconds      user   machine   count  average
php5.cgi                 577.7300   99.841%    2.407%    9554    0.060
ls                         0.5100    0.088%    0.002%      23    0.022
tar                        0.0900    0.016%    0.000%       2    0.045
wget                       0.0900    0.016%    0.000%       2    0.045
rm                         0.0600    0.010%    0.000%       2    0.030
bash                       0.0600    0.010%    0.000%       1    0.060
gzip                       0.0600    0.010%    0.000%       2    0.030
mv                         0.0300    0.005%    0.000%       1    0.030
id                         0.0200    0.003%    0.000%       1    0.020
ftponly                    0.0000    0.000%    0.000%       1    0.000
----------------------------------------------------------------------
Total:                   578.6500  100.000%    2.411%    9589
Average per day:         578.6500    1 days
CPU percentage assumes 24000 cpu seconds per day total.

[razzle]$ more /home/8ta/logs/resources/8ta.sa.analyzed.0    
Process               CPU seconds      user   machine   count  average
php5.cgi                1223.0300  100.000%    5.096%   20126    0.061
----------------------------------------------------------------------
Total:                  1223.0300  100.000%    5.096%   20126
Average per day:        1223.0300    1 days
CPU percentage assumes 24000 cpu seconds per day total.

more /home/8ta/logs/resources/8ta.sa.itemized.0 | wc
  20126  161008 1247812

This means 20126 php script hits per day.

How much CPU can I use?

Now, Dreamhost are very flexible on this. Basically, as long as your site isn't affecting the performance of the server, you're fine!

Another one:

Process               CPU seconds      user   machine   count  average
tar                       62.3500   32.184%    0.260%       1   62.350
chmod                     54.7100   28.240%    0.228%      12    4.559
gzip                      32.4200   16.735%    0.135%       1   32.420
rsync                     21.9100   11.310%    0.091%       4    5.478
rsync                     10.4200    5.379%    0.043%       1   10.420
top                        6.6500    3.433%    0.028%      18    0.369
ls                         1.4000    0.723%    0.006%      66    0.021
find                       1.1300    0.583%    0.005%       1    1.130
php5.cgi                   0.7100    0.366%    0.003%      11    0.065
w                          0.5400    0.279%    0.002%      24    0.023
mv                         0.4100    0.212%    0.002%       4    0.103
bash                       0.3600    0.186%    0.001%       4    0.090
tail                       0.2500    0.129%    0.001%      10    0.025
ping                       0.2000    0.103%    0.001%       8    0.025
dig                        0.0500    0.026%    0.000%       2    0.025
mkdir                      0.0400    0.021%    0.000%       2    0.020
rm                         0.0400    0.021%    0.000%       2    0.020
vi                         0.0400    0.021%    0.000%       1    0.040
wc                         0.0300    0.015%    0.000%       1    0.030
more                       0.0300    0.015%    0.000%       1    0.030
grep                       0.0200    0.010%    0.000%       1    0.020
cat                        0.0200    0.010%    0.000%       1    0.020
bash                       0.0000    0.000%    0.000%       1    0.000
dig                        0.0000    0.000%    0.000%       8    0.000
----------------------------------------------------------------------
Total:                   193.7300  100.000%    0.807%     185
Average per day:         193.7300    1 days
CPU percentage assumes 24000 cpu seconds per day total.