[FFmpeg-trac] #6009(ffmpeg:new): [Request] Direct-I/O for ffmpeg output files
FFmpeg
trac at avcodec.org
Fri Dec 9 20:32:48 EET 2016
#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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