Messages in this thread | | | Subject | Re: O_NONBLOCK, read(), select(), NFS, Ext2, etc. | Date | Fri, 12 Jan 2001 09:40:55 +0000 (GMT) | From | Alan Cox <> |
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> using the O_NONBLOCK flag, then read() and write() will always return > immediately and not block the calling process. This does not appear to > be true; but perhaps I am doing something wrong. If I open() a file (on > 2.2.18) from a floppy or NFS mount (to test in a slow environment) with > O_NONBLOCK|O_RDONLY, read() will still block. If I try to select() on > the file descriptor, select() always returns 0.
The definition of immediate is not 'instant'. Otherwise no I/O system would ever return anything but -EWOULDBLOCK. Its that it won't wait when there is no data pending. On a floppy there is always data pending
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