I am using
initramfs to boot Centos via PXE. The
initramfs used memory is listed within the "cached" value in
/proc/meminfo or via
Since I need to calculate performance data, I need to know whether the memory used by the
initramfs is reclaimable (i.e. can be swapped out to disk) or not. Typically only a very small part of the
/ filesystem tree is actually in use, so a majority of the
initramfs could be swapped out.
Reading on this I got conflicting information. Some sources claimed that
initramfs behaves like
initrd and is based on
ramfs, which means claimed memory cannot be paged out to swap. Other sources claim that
initramfs is essentially
tmpfs which in turn would imply that it can be paged out to swap.
Which is true? Can the unused parts of the
initramfs filesystem be paged out to swap space?