From: Jeff Moyer <jmoyer@redhat.com>
To: Benjamin LaHaise <bcrl@kvack.org>
Cc: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>,
        Kent Overstreet <kent.overstreet@gmail.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: aio: questions with ioctx_alloc() and large num_possible_cpus()
References: <db64a8f3-cd15-2ccc-e120-ba0466f811d0@linux.vnet.ibm.com>
        <20161005174146.GK23336@kvack.org>
        <737b5bf7-329e-c59d-7601-aea0f4ffbeab@linux.vnet.ibm.com>
        <20161005181741.GL23336@kvack.org>
Date: Fri, 28 Oct 2016 14:59:40 -0400
In-Reply-To: <20161005181741.GL23336@kvack.org> (Benjamin LaHaise's message of
        "Wed, 5 Oct 2016 14:17:41 -0400")
Message-ID: <x49twbw710j.fsf@segfault.boston.devel.redhat.com>
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Benjamin LaHaise <bcrl@kvack.org> writes:

> Today's high end systems are tomorrow's desktops...  It probably makes 

Well, to some degree I agree with you.  >100 processor high end systems
have been around for a long time, but we still don't have those on the
desktop.  ;-)

> sense to implement per-user limits rather than the current global limit, 
> and maybe even convert them to an rlimit to better fit in with the 
> available frameworks for managing these things.

I actually wrote a patch to do this back in 2007:
  http://www.gossamer-threads.com/lists/linux/kernel/1043934

It used the mlock rlimit.  I ultimately decided to rescind it, since
there were years of experience with the current tunable, and plenty of
documentation on it, too.  We could put aio-max-nr on the deprecated
path, though, if folks want to go that route.  Let me know and I can
investigate resurrecting that patch.  Though I would like input on
whether a new rlimit is desired.

Cheers,
Jeff