jemalloc is not portable to all ARM64 systems. It is not compatible on devices 
which do not use a 4k page size in the default configuration.

The maintainers understand this. And have decided that optimizing* a subset of
devices is more important than portability:
  https://github.com/jemalloc/jemalloc/issues/467

We officially support 64k on arm64:
  
https://ubuntu.com/server/docs/choosing-between-the-arm64-and-arm64-largemem-installer-options

According to d/rules we are using 16k page size when !amd64:
  https://git.launchpad.net/ubuntu/+source/jemalloc/tree/debian/rules#n17
  
https://github.com/jemalloc/jemalloc/blob/17881ebbfd76529904e826f425f3266834cf3a75/INSTALL.md?plain=1#L225-L233

iiuc *optimizing, a 4k page size means that only 4k of memory is reserved when
the kernel is asked for memory. A 64k page size reserves 64k memory. If not all
of that memory space is used, libc will reuse available space--which leads to
less system calls. So, a small page size optimizes for systems with little
available memory and large page sizes optimizes for compute. Please correct me
if I misunderstand this.

Cheers to @tobhe for the help.

** Bug watch added: github.com/jemalloc/jemalloc/issues #467
   https://github.com/jemalloc/jemalloc/issues/467

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https://bugs.launchpad.net/bugs/2088056

Title:
  [MIR] jemalloc

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