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From: Neil Brown <neilb@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Date: Mon, 26 Mar 2007 10:05:02 +1000
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Cc: Miklos Szeredi <miklos@szeredi.hu>, linux-kernel@vger.kernel.org
Subject: Re: [patch] add file position info to proc
In-Reply-To: message from Andrew Morton on Sunday March 25
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On Sunday March 25, akpm@linux-foundation.org wrote:
> On Sat, 24 Mar 2007 23:04:09 +0100 Miklos Szeredi <miklos@szeredi.hu> wrote:
> 
> > This patch adds support for finding out the current file position,
> > open flags and possibly other info in the future.
> > 
> > These new entries are added:
> > 
> >   /proc/PID/fdinfo/FD
> >   /proc/PID/task/TID/fdinfo/FD
> > 
> > For each fd the information is provided in the following format:
> > 
> > pos:	1234
> > flags:	0100002
> 
> I've seen the idea mentioned once or twice, but not with any great
> enthusiasm.  Why does Linux want this feature?

Same reason we want ltrace and lsof.  To be able to look inside a
process and see what it is doing.
e.g. how far has that program got through reading that enormous file?
is it really making progress, or is it going much more slowly than I
would expect and so should I look more deeply.

I'm in favour.

NeilBrown