Dear monks, A lot has been written about Perl memory management, but I could not find anything that would document the behavior I'm seeing. Using native malloc and allocating large chunks (more than 128k, so that mmap is used, not brk), I'm seeing the chunks being unallocated a bit too late. One example worth thousand double-words: 
$ strace -e mmap2,munmap perl -e '{"x" x 1048576}{"x" x 1048576}{"x" x
+ 1048576}' 2>&1 |tail -6
mmap2(NULL, 1052672, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 
+-1, 0) = 0xb740c000
mmap2(NULL, 1052672, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 
+-1, 0) = 0xb730b000
mmap2(NULL, 1052672, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 
+-1, 0) = 0xb720a000
munmap(0xb720a000, 1052672)             = 0
munmap(0xb730b000, 1052672)             = 0
munmap(0xb740c000, 1052672)             = 0

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Anyone has an explanation for that, or pointer to documentation before I dig into the code?

In reply to Freeing memory, revisited (Linux) by lkundrak

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