CODEWITHSUNDEEP
optimizationmakefilebuild-process
Brian Vandenberg
Brian Vandenberg

Reputation: 4121

Measuring build times to identify bottlenecks

I'm working on improving the build for a few projects. I've improved build times quite significantly, and I'm at a point now where I think the bottlenecks are more subtle.

The build uses GNU style makefiles. I generate a series of dependency files (.d) and include them in the makefile, otherwise there's nothing fancy going on (eg, no pre-compiled headers or other caching mechanisms).

The build takes about 95 seconds on a 32-core sparc ultra, running with 16 threads in parallel. Idle time hovers around 80% while the build runs, with kernel time hovering between 8-10%. I put the code in /tmp, but most of the compiler support files are NFS mounted and I believe this may be creating a performance bottleneck.

What tools exist for measuring & tracking down these sorts of problems?

Upvotes: 2

Views: 214

Answers (1)

Maxim Egorushkin
Maxim Egorushkin

Reputation: 136276

From my own experience, compiling C/C++ code requires reading a lot of header files by C preprocessor. I've experienced situations when it took more than 50% of g++ run-time to generate a complete translation unit.

As you mentioned that it idles 80% when compiling it must be waiting for I/O then. iostat and DTrace would be a good starting point.

Upvotes: 1

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