CVS compression levels

Using CVS over modem lines is a lot faster when you're using compression of your traffic. CVS offers you 9 compression levels, ranging from 1 to 9, where 1 is using the least compression, but is the fastest to execute, and level 9 gives you the best compression, but it puts a bigger load on your CVS server in order to compress the data.

I started wondering what kind of a compression level I would use. I do not have the right measurement equipment to figure out what level is best, so, the naive person I am, I turned to http://google.com'>Google in order to investigate what kind of levels other people use. I will use the level that most people use. Democratic, isn't it?

So here's what http://google.com'>Google turned up with (September 12, 2003, numbers may differ through space and time):

• {?"cvs -z1"?}: 44 hits
• {?"cvs -z2"?}: 76 hits
• {?"cvs -z3"?}: 36300 hits
• {?"cvs -z4"?}: 692 hits
• {?"cvs -z5"?}: 448 hits
• {?"cvs -z6"?}: 877 hits
• {?"cvs -z7"?}: 166 hits
• {?"cvs -z8"?}: 123 hits
• {?"cvs -z9"?}: 2740 hits

Most web pages that discuss cvs and their compression level thus assume a compression level of 3. Surprisingly many people also advise on level 9, compared to all other levels. However, I don't want the load on my CVS server to be too high.

As a conclusion, I'm currently using level 3. But I have no clue whether this is best in my situation.

Order of parameters

As a last note, I'd like to point out that you have to provide the compression level at the command line before you provide the command to cvs. As such, use e.g. "cvs -z3 update" and not "cvs update -z3" as in the latter command, the compression level is passed to the update command, which does not understand this parameter. The order of parameters is important.

See also

Using CVS