performance tip for the package development stage
Hi all,
I'm sorry if this is well known. I haven't seen it anywhere, and I
thought I'd share it with everybody.
During the initial package development stage, there is a lot of repeated
compilation of the same package over and over again. With some packages
that's not so bad, but some take a long time to compile. I'd like to
draw people's attention to a small program that can greatly help. It's
called ccache, and this is the effect it has on my system.
When compiling a package called "xparam" for the first time, these are
the timing results (dpkg-buildpackage, including clean)
real 9m44.129s
user 7m48.328s
sys 1m5.499s
The second time around, these are the results:
real 1m50.366s
user 0m58.678s
sys 0m27.084s
It works by caching the output (both stdout/stderr, and the file output)
of the compiler, and performing md5 on the input. If the same input is
given, it will produce the same output.
In order to set it up, apt-get install ccache. Then create a directory
somewhere and put there symlinks from cc, gcc, c++ and g++ to
/usr/bin/ccache. When you want to make use of this feature, add this
directory to the beginning of your path and work as you would always work.
Personally, I wouldn't use this for compiling the package after you have
done with the debian related development, but the ccache author claims
it's totally safe for that as well.
I hope people find this tip useful.
Shachar
--
Shachar Shemesh
Lingnu Open Source Consulting ltd.
Have you backed up today's work? http://www.lingnu.com/backup.html
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