On 2012-09-04 16:11, Ian Abbott wrote:
On 2012-09-04 15:39, Jan Kara wrote:
On Tue 04-09-12 10:49:39, Ian Abbott wrote:
Add support for the O_DIRECT flag. There are two cases to deal with:
Out of curiosity, do you have a use for this feature or is it mostly
academic interest?
I'm planning to use it for an embedded project that needs to stream
large files off a CompactFlash card, but the data doesn't need to be in
the buffer cache as its only read once, and the system has very limited
memory bandwidth so I can't afford the the extra copy. The old version
of this project only supported FAT, but that limited the file size to
about 4GiB. The filesystem needs to be something reasonably
Windows-friendly, at least for adding the files to the CompactFlash card
in the first place.
Actually, remembering back (the old project was about 3 years ago), the
main reason for using O_DIRECT was it was causing too much memory
fragmentation on my MMU-less embedded system. That and the extra
overhead of managing the buffer cache for data that was only read once.
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-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
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