[Boost-users] [interprocess] Reading huge files

Dear all, I am new to boost memory mapping, so this question might look simplistic. I need to read huge amounts of data (for instance, a 20GB file), and since memory mapping is quite fast, I was going to use it. However, I don't know what it would be faster when, due to memory constraints, I need to partition the file into regions. Moreover, I should treat the file as a string (I need to perform string operations). What I'm trying now is just to read the entire file: boost::interprocess::file_mapping mmap(input_filename.c_str(), boost::interprocess::read_only); boost::interprocess::mapped_region map(mmap, boost::interprocess::read_only); std::size_t l = map.get_size(), tot_read = 0; void *ptr = map.get_address(); while (tot_read < l) { register std::size_t x = std::min(l - tot_read, static_caststd::size_t(prealloc)); std::copy_n(static_cast(ptr) + tot_read, x, line.begin()); // Do something here... tot_read += x; } So, when the file is huge, do I need to create a mapped_region inside the loop? I didn't see anywhere in the documentation the possibility to move the mapped region. Another side-question, if you don't mind. I'm not sure that what I'm doing is efficient, especially the need to copy from the region to a string. If you have suggestions, I'm more than happy to hear these. Thanks & Cheers!