Re: [LSF/MM TOPIC][ATTEND] protection information and userspace

[Joel Becker <jlbec@evilplan.org>]

On Thu, Feb 07, 2013 at 02:12:57PM -0500, Martin K. Petersen wrote:
> >>>>> "Joel" == Joel Becker <jlbec@evilplan.org> writes:
> 
> Joel> I'm happy to chat about it.  Unfortunately, like Darrick says,
> Joel> sys_dio() coding hasn't happened.  I do think we're better off
> Joel> with some kind of explicit API than some magic state on the file.
> Joel> I mean, even something like:
> 
> Joel> 	ssize_t write_with_pi(int fd, const void *buf, size_t count,
> Joel> 			      const void *pi, size_t pi_count);
> 
> Joel> It's not as nice as a non-historical API (eg sys_dio), but it also
> Joel> probably plays nicer with buffered I/O.
> 
> Pretty much everyone I have talked to that are interested in explicitly
> attaching PI (as opposed to relying on the kernel doing it) are using
> Linux aio.
> 
> I am not opposed to having more read()/write() like interface as
> well. But I think it's important to cater to the I/O paradigm used by
> the applications interested in this. It's a lot easier to tweak a few
> IOCB fields than it is to rewrite how an application does I/O.

You know I'm not going to argue with this.  I was merely stating that
I'm flexible in how we start :-)

Joel

> 
> -- 
> Martin K. Petersen	Oracle Linux Engineering
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 help the rabbit."
	- R. E. Shay

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			jlbec@evilplan.org