Re: O_NONBLOCK is NOOP on block devices
From: Alan Cox
Date: Wed Mar 03 2010 - 06:47:34 EST
> If O_NONBLOCK is meaningful whatsoever (see man page docs for
> semantics) against block devices, one would expect a nonblocking io
It isn't...
The manual page says "When possible, the file is opened in non-blocking
mode" . Your write is probably not blocking - but the memory allocation
for it is forcing other data to disk to make room. ie it didn't block it
was just "slow".
O_NONBLOCK on a regular file does influence how it responds to leases and
mandatory locks.
> probably be documented for clarity and it would be straight forward
> for it to return an error if these contradictory behaviors are
> simultaneously specified, unintentionally of course.
and risk breaking existing apps.
> Thoughts anyone?
Alan
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