From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: [RFC][PATCH 0/3] TCP/IP Critical socket communication mechanism Date: Wed, 14 Dec 2005 20:49:10 +0000 Message-ID: <43A08546.8040708@superbug.co.uk> References: <9a8748490512141216x7e25ca2cucb675f11f0c9d913@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Sridhar Samudrala , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: To: Jesper Juhl In-Reply-To: <9a8748490512141216x7e25ca2cucb675f11f0c9d913@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Jesper Juhl wrote: > On 12/14/05, Sridhar Samudrala wrote: > >>These set of patches provide a TCP/IP emergency communication mechanism that >>could be used to guarantee high priority communications over a critical socket >>to succeed even under very low memory conditions that last for a couple of >>minutes. It uses the critical page pool facility provided by Matt's patches >>that he posted recently on lkml. >> http://lkml.org/lkml/2005/12/14/34/index.html >> >>This mechanism provides a new socket option SO_CRITICAL that can be used to >>mark a socket as critical. A critical connection used for emergency > > > So now everyone writing commercial apps for Linux are going to set > SO_CRITICAL on sockets in their apps so their apps can "survive better > under pressure than the competitors aps" and clueless programmers all > over are going to think "cool, with this I can make my app more > important than everyone elses, I'm going to use this". When everyone > and his dog starts to set this, what's the point? > > I don't think the initial patches that Matt did were intended for what you are describing. When I had the conversation with Matt at KS, the problem we were trying to solve was "Memory pressure with network attached swap space". I came up with the idea that I think Matt has implemented. Letting the OS choose which are "critical" TCP/IP sessions is fine. But letting an application choose is a recipe for disaster. James