Comments on: Automatic Dependency Management with ElectricAccelerator http://www.electric-cloud.com/blog/2008/12/15/automatic-dependency-management-with-electricaccelerator/ This is your source for private development cloud best practices and technical tips and tricks for Electric Cloud solutions Thu, 03 May 2012 01:47:53 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Eric Melski http://www.electric-cloud.com/blog/2008/12/15/automatic-dependency-management-with-electricaccelerator/#comment-19 Eric Melski Fri, 19 Dec 2008 18:57:21 +0000 http://ecloud.wordpress.com/?p=148#comment-19 Thanks for the suggestion. I reran my benchmark using g++ -MD and incorporated the results into the table above. As you can see, it is definitely faster than g++ -MM, but still noticeably slower than ElectricAccelerator's autodepend feature (about 12% worse in this example). The other problem with g++ -MD, of course, is that the dependencies lag behind the current sources by one build; with the traditional g++ -MM implementation, the dependencies are regenerated first, so when you actually get to the compile phase of the build, you have good dependency information. I can imagine ways around that limitation, but they are all pretty clunky. Thanks for the suggestion. I reran my benchmark using g++ -MD and incorporated the results into the table above. As you can see, it is definitely faster than g++ -MM, but still noticeably slower than ElectricAccelerator’s autodepend feature (about 12% worse in this example).

The other problem with g++ -MD, of course, is that the dependencies lag behind the current sources by one build; with the traditional g++ -MM implementation, the dependencies are regenerated first, so when you actually get to the compile phase of the build, you have good dependency information. I can imagine ways around that limitation, but they are all pretty clunky.

]]> By: hannes http://www.electric-cloud.com/blog/2008/12/15/automatic-dependency-management-with-electricaccelerator/#comment-18 hannes Tue, 16 Dec 2008 12:32:29 +0000 http://ecloud.wordpress.com/?p=148#comment-18 Thanks for the interesting numbers. I wouldn't have guessed that makedepend turns out to be slower than g++ -MM. Have you ever measured g++ -MD (i.e. dependencies generated as a side-effect of compilaton)? That should have similarly low overhead to the autodepend solution, right? It's more complex and fragile, of course, but for those of us stuck with plain old make it seems like the best method. Thanks for the interesting numbers. I wouldn’t have guessed that makedepend turns out to be slower than g++ -MM.

Have you ever measured g++ -MD (i.e. dependencies generated as a side-effect of compilaton)? That should have similarly low overhead to the autodepend solution, right? It’s more complex and fragile, of course, but for those of us stuck with plain old make it seems like the best method.

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