Re: How to signal kernel that shared library is not in use by any process anymore ?

[Shachar Shemesh]

On 23/12/2018 09:49, Lev Olshvang wrote: Boker tov,   Thanks for all of your replies that helped me to understand what question I really wanted to ask.   So this is a question.   I have  C++ program which calls many services of third party library. This library is needed only on initialization phase of my program.     Linker has resolved symbols of this library and now it is bound to executable and in a run tine this lib will be mapped  will have use count > 0   while executable is in use. I would like to unmap it to release memory, but i do not know how to do it in user space.   As an alternative I know that by using dynamic loader calls  dlopen() .. dlclose()  I can achieve the desired effect   The problem that I need to add a lot of dlfind() calls, and I looked for a way dynamic loader can do it. I am not that lazy, but since the code is C++,  function names are mangled and I was tring to avoid this by looking as a subject of this mail said, way to ask kernel to unmap this lib   I wish we have __init attribute in a user land !   First, yes, it will have a use count of more than zero. So what? All the pages are clean, and have a file that has a copy. The kernel will gladly remove them from memory despite being mapped (unless you mlock them, that is). If, as you say, they are not used after init, then nothing will fault them and cause them to come back. I am not that lazy, It's not about being lazy. It's about opening yourself up for introducing bugs. I wouldn't do that. Assuming you're still not convinced, here's what I would do: Write your own library (liblevinit.so). Put all the calls that need to go into that other library into liblevinit.so. dlopen and dlsym lev init, call the trigger function, and then dlclose it. You now have to manage only one symbol, and Like I said above, I don't think that is necessary. If you want to be paranoid about it, however, that's what I'd do. Shachar

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