Re: [MLUG] Linux time command -- "kernel mode" and "user mode"

[Mike Miller <EMAIL:PROTECTED>]

On Fri, 3 Nov 2006, Stephen Montgomery-Smith wrote:

> On Fri, 3 Nov 2006, Mike Miller wrote:
>
> > We have written a program in C++ and we have also written it with a 
> > slightly different algorithm in Python.  We want to see how much slower 
> > the Python program is than the C++ program.  We get these results:
> >
> > Python:
> > ------
> > real    10m43.357s
> > user    9m51.050s
> > sys     0m23.420s
> >
> > C++:
> > ------
> > real    8m16.668s
> > user    5m38.360s
> > sys     2m37.780s

> This is my understanding.
>
> You want to add the user and kernel times together.
[snip good info]
> What does your program do?

It reads in a large amount of data (a few million lines) and processes 
every line by replacing certain strings with others based on a hash table. 
Then it writes the reformatted data into a collection of about 300 files. 
So one big file comes in and 300 smaller gzipped files go out.

The C++ program reads the whole big file into memory, reformats it and 
writes it out to 300 files, one at a time.  The Python program reads in 
the big file one line at a time and writes each processed line immediately 
to one of the 300 files, keeping all 300 open at once.

The Python script surely uses minimal memory while the C++ program uses 
lots of memory.  The Python program opens many files at once, but this 
seems not to be a problem under most conditions, while the C++ file keeps 
open only one output file at a time.

Thanks for the tips, Stephen.

Mike

_______________________________________________
members mailing list
EMAIL:PROTECTED
http://mlug.missouri.edu/mailman/listinfo/members