Re: [RFC][PATCH 0/3] TCP/IP Critical socket communication mechanism

[James Courtier-Dutton <James@superbug.co.uk>]

Jesper Juhl wrote:
> On 12/14/05, Sridhar Samudrala <sri@us.ibm.com> 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
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