Difference between revisions of "Performance research"

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== Dump ==
 
== Dump ==
  
== <code>parse_smaps</code> ==
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Surprisingly, but the mem-drain time is not the biggest. It's "only" ~0.02 seconds. There are places in code that take longer.
  
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
+
=== <code>parse_smaps</code> ===
 +
 
 +
Time spent in this routine is up to 0.2 seconds on dump. This one exploits /proc heavily. For a container with 11 tasks the syscall stats look like
  
 
     834 read
 
     834 read
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   1438 openat(4, "map-symlink", O_RDONLY) = 5
 
   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
 
     11 openat(AT_FDCWD, "/proc/$pid/map_files", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 4
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 +
=== <code>parasite_fuxup_vdso</code> ===
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The 2nd longest routine. It takes ~ 0.07 seconds on dump.
  
  
 
== Restore ==
 
== Restore ==

Revision as of 20:57, 30 January 2014

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

Dump

Surprisingly, but the mem-drain time is not the biggest. It's "only" ~0.02 seconds. There are places in code that take longer.

parse_smaps

Time spent in this routine is up to 0.2 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

parasite_fuxup_vdso

The 2nd longest routine. It takes ~ 0.07 seconds on dump.


Restore