realloc, copy and VM


When you realloc for more size, it may be necessary to allocate a new block,
copy memory and deallocate the old, for example if there is not enough free
space after the original block (maybe the only example ?). But, is it really
necessary to _copy_ bytes ? When in a virtual memory environment (off-topic
here, be I still think the question is worth), you don't access directly
physical memory, but allocated pages, so would it be possible on some
implementations, to just change page allocation ? Some kind of immobile
trip. It could permit optimizations even when not knowing beeforehand the
exact amount of memory needed.

.

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