Sun Feb 11 14:34:33 CET 2007

More build statistics and data

The next idea to try in our journey to get fast builds was to try building everything in memory. For this purpose, we will compare the data with our previous results. The fastest build done on disk with 13 parallel directories built at the same time was 1 hour 38 minute without ccache or 33 minutes with ccache (ccache saving was approx. 66% when building on disk).

The same builds done in memory (on tmpfs) were 1 hour and 35 minutes (without ccache) or 29 minutes (with ccache). This time, ccache was on the disk, so I tried with ccache cache in memory but the result was the same (I'm building on machine with 16GB or RAM, enough for buffer caches etc.)

To sum up if you are about to build a new build machine for Linux: it is better to have more (even slower) processors/cores than having the most powerful processors available! Instead of throwing your money out of the window, spend your time on optimizing your build parameters for your environment (and you can also help us with fixing parallel build issues ;-). This means that for our new build server, I'll target the slowest possible quad Xeon (5310), one single processor in a dual board.

The tmpfs gain is not that significant if you have enough RAM so it is not worth the effort. And to be able to build in RAM, you must have enough RAM anyway ;-)

If you have other ideas what to measure/compare on this machine, just ping me on IRC or via mail.

In the next blog entry, I'll analyze the overall build data a bit.

Posted by Pavel | Permanent link | File under: