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On a native C++ project, linking right now can take a minute or two. Yet, during this time CPU drops from 100% during compilation to virtually zero. Does this mean linking is primarily a disk activity?
If so, is this the main area an SSD would make big changes? But, why aren't all my OBJ files (or as many as possible) kept in RAM after compilation to avoid this? With 4 GB of RAM I should be able to save a lot of disk access and make it CPU-bound again, no?
Update: so the obvious follow-up is, can the VC++ compiler and linker talk together better to streamline things and keep OBJ files in memory, similar to how Delphi does it?
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The linking step is necessary to resolve all the references to external functions and to include the machine code for those functions in the final executable. Why is "linking" a "separate step"? You need at least two "separate steps" to get the assembler output, and two separate steps after that to get an executable.
Linker is a program in a system which helps to link object modules of a program into a single object file. It performs the process of linking. Linkers are also called as link editors. Linking is a process of collecting and maintaining piece of code and data into a single file.
Symbol resolution ↑top The linker resolves symbol references by associating each ref with exactly one symbol definition from the symbol tables of its input relocatable obj files. Symbol resolution is easy for references to local variables that are defined in the same module as the ref.
Linking is indeed primarily a disk-based activity. Borland Pascal (back in the day) would keep the entire program in memory, which is why it would link so fast.
Your OBJ files aren't kept in RAM because the compiler and linker are separate programs. If your development environment had an integrated compiler and linker (instead of running them as a separate processes), it could indeed keep everything in RAM.
But you would lose the ability to separate the development environment from the compilers and/or linkers - you would have to use the same compiler/linker, and you wouldn't be able to run the compiler outside the environment.
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