[FFmpeg-trac] #6009(ffmpeg:new): [Request] Direct-I/O for ffmpeg output files

[FFmpeg]

#6009: [Request] Direct-I/O for ffmpeg output files
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             Reporter:  janos666     |                     Type:
               Status:  new          |  enhancement
            Component:  ffmpeg       |                 Priority:  normal
             Keywords:  directio,    |                  Version:
  direct_io, dio                     |  unspecified
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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 Please support Direct-I/O for ffmpeg output files.

 Example use case: I have a multi-function home server which (among other
 things) dumps several continuous video streams to files (surveillance
 camera recordings). Since Linux file-systems have a shared LRU (least
 recently used) pagecache replacement logic, this continuous and meaningful
 amount of I/O tends to "wash out" potentially useful file-system
 (meta)data from the pagecache (since these video files are 99.9% write-
 only, I only ever open them on very rare occasions when I have reason to
 suspect they might recorded something unusual).

 So, as I understand, the solution would be opening the output files in DIO
 (Direct-I/O) mode which is supposed to prevent keeping the file data in
 the pagecache (well, depending on the actual file-system driver and it's
 settings, it might goes through some caching still but it should be
 restricted to write caching and/or very limited in size for read-caching,
 hence still a lot better than regular buffered IO).

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Ticket URL: <https://trac.ffmpeg.org/ticket/6009>
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