On Mon, 14 Jun 1999 20:08:36 +0200 (CEST), Arjan van de Ven
<arjan@fenrus.demon.nl> said:
> I want to do a non-blocking read from a file, from within the kernel.
> Is this, at all, possible? I have been tracing how userspace does
> this, but the userspace does not seem to be non-blocking either.
For regular files, that is correct. But...
> * non-blocking read is issued
> * if the pages are in the pagecache, they are copied to my buffer
> * if they are not, an asynchronous read-ahead is issued and the
> read-funtion returns -EAGAIN
...to do this in the kernel, look at the readahead code: that populates
the page cache asynchronously. There just isn't any high-level function
which does that automatically for you: you need to do all the setup
yourself.
--Stephen
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