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

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Message-ID: <18020.7945.364135.889997@stoffel.org>
Date:	Mon, 4 Jun 2007 10:17:45 -0400
From:	"John Stoffel" <john@...ffel.org>
To:	"Aaron Wiebe" <epiphani@...il.com>
Cc:	"Alan Cox" <alan@...rguk.ukuu.org.uk>, linux-kernel@...r.kernel.org
Subject: Re: slow open() calls and o_nonblock

>>>>> "Aaron" == Aaron Wiebe <epiphani@...il.com> writes:

Aaron> 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.

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

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

So how many files are in the directory where you're seeing the delays?
And what's the average size of the files in there?  

John
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