For test purposes, on illumos, I have been using following simple script:
: fs-load
0 bcachestat
seconds
s" /platform/i86pc/kernel/amd64/unix" 1 load
s" /boot_archive" s" rootfs" s" -t " 3 load
seconds
swap - ." total: " . ." sec" cr
0 unload
0 bcachestat
;
The issue is to read in sufficiently large file to get meaningful result for time difference; also depending on media obviously.
The consistency of the loaded data has been verified by the feature of the illumos kernel, it can verify the SHA1 checksum of loaded module.