Tidying up .mozconfig
06.13.07 - 03:38pm
Long long ago, when I was first learning how to compile Mozilla from source, through some magical process I ended up with a .mozconfig file which worked. Maybe I copied it from DevMo, or maybe someone gave me their copy. I really don’t remember!
Anyway, now that the build process is ever-so-slightly more familiar to me, I’ve cleaned up some of the .mozconfig files I have around. One line I just looked at was:
mk_add_options MOZ_CVS_FLAGS=@CVS_FLAGS@' -q -z4'
The -z4 specifies the compression level used when transferring the source. Using 0 disables compression, and 9 uses maximal compression. In theory, it’s a tradeoff between CPU time and network speed. So what’s the best value to use?
A quick benchmark seems to indicate that it doesn’t matter. -z4, -z8, and -z9 all took 135 seconds (+/- a couple seconds) to checkout the Firefox 3 trunk code. A test with -z0 was about 10 seconds slower, but I didn’t repeat it to see if it was a quirk.
So, I’m just going to remove this line from my .mozconfig, and rely on the default (which is “-q -z3″). Yay simplicity. Anyone else find similar results? Perhaps -z9 helps for dialup-speeds? [My system is a 2.16Ghz Macbook Pro, connected over 802.11g WiFi.]
I don’t know about the levels, but I have to use compression at times in order to make diff work with many files.
In most cases, a CPU should be a lot faster than the network — If it makes a difference in size (and I’m not saying that it does in this case) and the algorithm isn’t insanely expensive, that should be an easy tradeoff.
cvs is very chatty, so unless you’ve got very slow throughput operations are going to depend on latency, not raw tranfer speed.