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

From: James Courtier-Dutton
Date: Wed Dec 14 2005 - 15:48:32 EST


Jesper Juhl wrote:
On 12/14/05, Sridhar Samudrala <sri@xxxxxxxxxx> 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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/