Re: [RFC] - Some notions that I would like comments on

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Tue, 13 Jul 1999 20:36:13 +0200

cd_smith@ou.edu wrote:
> Speculative I/O would appear to be a blocking I/O call, but as
> soon as it queued the I/O request, it would return. The result page would
> be marked as unreadable and unwriteable, and the actual I/O blocking would
> be done on a page fault.

You can do this by calling mmap() and then starting a thread to access a
byte from each page sequentially.

Or you can do it by calling mmap() and then starting a thread to read()
a byte at inter-page offsets. This is probably faster because the
kernel does readahead.

If you want exactly the same results as read, use MAP_PRIVATE and have
the reader thread read-then-write, to make local copies of the pages.

disclaimer: I've never done this.

-- Jamie

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