linux-kernel - Re: slow open() calls and o

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Message-ID: <e7ca40f70706040704w450dd609g46b6e7a3689ff11@mail.gmail.com>
Date:	Mon, 4 Jun 2007 10:04:52 -0400
From:	"Aaron Wiebe" <epiphani@...il.com>
To:	"Alan Cox" <alan@...rguk.ukuu.org.uk>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: slow open() calls and o_nonblock

On 6/4/07, Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
>
> > Now, I'm a userspace guy so I can be pretty dense, but shouldn't a
> > call with a nonblocking flag return EAGAIN if its going to take
> > anywhere near 415ms?
>
> Violation of causality. We don't know it will block for 415ms until 415ms
> have elapsed.

Understood - but what I'm getting at is more the fact that there
really doesn't appear to be any real implementation of nonblocking
open().  On the socket side of the fence, I would consider a regular
file open() to be equivalent to a connect() call - the difference
obviously being that we already have a handle for the socket.

The end result, however, is roughly the same.  We have a file
descriptor with the endpoint established.  In the socket world, we
assume that a nonblocking request will always return immediately and
the application is expected to come back around and see if the request
has completed.  Regular files have no equivalent.

-Aaron
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