Performance research

Written here are performance issues found.

Timing stats of live migration of a small container with 11 tasks is

• Total time ~3.5 seconds
• Frozen time ~3.0 seconds
  • Pre-dump stages ~0.5 seconds each
  • Restore time ~1.9 seconds
  • Images transfer time ~0.3 seconds

Below is the list of issues found

parse_smaps

Time spent in this routine is about 0.1 seconds on dump. This one exploits /proc heavily. For a container with 11 tasks the syscall stats look like

   834 read
  1451 fstat
  1462 close
  1642 openat

while opens and stats happen on

   193 openat(4, "map-symlink", O_RDONLY) = -1 ENOENT (No such file or directory)
  1438 openat(4, "map-symlink", O_RDONLY) = 5
    11 openat(AT_FDCWD, "/proc/$pid/map_files", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 4