Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755743AbZCJNoY (ORCPT ); Tue, 10 Mar 2009 09:44:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754945AbZCJNoF (ORCPT ); Tue, 10 Mar 2009 09:44:05 -0400 Received: from mx2.redhat.com ([66.187.237.31]:51373 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755276AbZCJNoE (ORCPT ); Tue, 10 Mar 2009 09:44:04 -0400 From: Jeff Moyer To: Andrew Morton Cc: linux-aio@kvack.org, zach.brown@oracle.com, bcrl@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch] aio: remove aio-max-nr and instead use the memlock rlimit to limit the number of pages pinned for the aio completion ring References: <20090309153630.912d36a0.akpm@linux-foundation.org> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Tue, 10 Mar 2009 09:43:56 -0400 In-Reply-To: <20090309153630.912d36a0.akpm@linux-foundation.org> (Andrew Morton's message of "Mon, 9 Mar 2009 15:36:30 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1426 Lines: 36 Andrew Morton writes: > It's risky to simply remove an existing tunable. What if someone's > mission-critical startup script which is provided by a super-slow or > even no-longer-in-business vendor does > > if (write(aoi-max-nr, something) == error) > crash_and_burn() > > ? > > It would be prudent to have a more cautious update scheme. Leave the > existing tunable in place. Keep it working if possible. If someone > uses it, blurt out a loud printk telling them that they're using a > deprecated interface and informing them how to update. > > Then at some later time we can remove the old interface. You are absolutely right. The more I think about this, the less enthused I am about it. I still believe the change is the right way to go, but there are years worth of deployments using the current scheme, and there are existing documents detailing how to work within that scheme. I hereby rescind this patch. I will follow-up with the memlock cleanup, though; let me know if you have comments on that patch. Zach mentioned that he hates my new function name (can_mlock_pages), so I guess at least that will change. ;) Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/