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Line 5: − + − + − + − is collected and sorted. Now, if any few processes have a mapping with same ''device'' and ''inode'',+ − + + +
→Checkpoint
Every process has one or more so called mmapings -- regions of virtual memory which it's allowed to use. Some mappings can be shared between a few processes.
Every process has one or more so called mmapings -- regions of virtual memory which it's allowed to use. Some mappings can be shared between a few processes.
During the checkpointing, CRIU need to figure out all the shared mappings in order to dump them as such.
During the checkpointing, CRIU needs to figure out all the shared mappings in order to dump them as such.
It does so by performing <code>fstatat()</code> for each entry in <code>/proc/$PID/map_files/</code>,
It does so by calling <code>fstatat()</code> on each entry found in the <code>/proc/$PID/map_files/</code>,
noting the ''device'' and ''inode'' fields of the structure returned by fstatat(). This information
noting the ''device:inode'' pair of the structure returned by fstatat(). Now, if some processes have a
mapping with the same ''device:inode'' pair, this mapping is marked as shared between them and is dumped as such.
this mapping is a shared one and should be dumped as such.
Dumping a mapping means writing an entry into proceess' mm.img file and storing its contents. For shared
mapping the contents is stored into pagemap-shmem.img and pages.img pair of images (see [[Memory dumps]]).
It's important to note that the above mechanism works not just for the file-based mappings,
It's important to note that the above mechanism works not just for the file-based mappings,