Difference between revisions of "Memory dumping and restoring"

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(Problems)
(Dumping)
Line 8: Line 8:
 
** which file is mapped
 
** which file is mapped
 
** shared memory "identifier" to detect the sharing
 
** shared memory "identifier" to detect the sharing
* mincore() system call says which pages are to be dumped and which are not (to be fixed as well)
+
* proc pagemap file says which pages are to be dumped and which are not (to be fixed as well)
 
* Ptrace SEIZE is used to dump the memory contents
 
* Ptrace SEIZE is used to dump the memory contents
  

Revision as of 19:10, 21 October 2012

How it works now

Dumping

Currently memory dumping depends on 3 big technologies:

  • /proc/pid/map_files/ directory with links is used to determine
    • which file is mapped
    • shared memory "identifier" to detect the sharing
  • proc pagemap file says which pages are to be dumped and which are not (to be fixed as well)
  • Ptrace SEIZE is used to dump the memory contents

Restoring

This one depends only on the /proc/pid/map_files/ to restore the shmem regions -- tasks just open some other's link and map it to create shmem region. The pages restoration just writes page data "in place".

Problems

Non linear mappings

Currently we don't support non-linear mappings (fail dump if present)