How to improve link performance for a large C++ application in VS2005

Question

We have fairly large C++ application which is composed of about 60 projects in Visual Studio 2005. It currently takes 7 minutes to link in Release mode and I would like to t

Answer 1

Generally, using DLLs instead of static libraries will improve linking times quite a bit.

Answer 2

I've had similar troubles linking large apps with Visual C++ before. In my case, I simply didn't have enough free RAM and excessive paging to disk was slowing the linking process to a halt. Doubling my RAM from 1GB to 2GB made a dramatic improvement. How much is your dev box running?

Answer 3

I don't think converting to DLLs would be useful. You could try looking for options to do with optimisation, and turning them off. The linker might be spending a long time looking over the libs for redundant code it can eliminate. Your app may end up bigger or slower, but that may not be a problem to you.

Answer 4

If you are truly talking about link times, then things like fast solution build and Xoreax won't really help much (except for Incredilink, which might). Assuming that you are truly measuring link start to link end, then I would suggest that the number of libs that you have is the issue.

The link phase is, at least initially, IO bound in loading up all of the object and lib files. You might be in a situation where you have 60 libraries along with the main project of some large number of .obj files. I suspect that you simply might be seeing, at least in part, typical windows slowness in loading up all of those libs and .obj files.

You can easily test this. Take all of those lib files and build one single lib file just as a test. Instead of linking with 60 of them, link with one and see where your time goes. That would be interesting.

NTFS is notoriosly slow. It shoudln't be 7m vs. 32 seconds on Linux slow, but it might be part of the issue. Using DLL's will help but you will suffer application startup time, although that will not be early as bad. I would be confident that you won't have 7m application start up times.

Answer 5

Step 1 in C++ build time reduction is more memory. After switching from 4GB to 12GB, I saw my link-all-projects time fall off a cliff: from 5:50 to 1:15.

Answer 6

Get a quicker computer with multiple processors and enable parallel builds (this might be on by default). To allow the greatest amount of parallism, make sure your project dependencies are correct and you haven't got unnecessary dependencies.