Subject: Re: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics

From: Andi Kleen <[email-masked]>
Date: 29 Mar 2005 17:11:59 +0200

On Mon, Mar 28, 2005 at 11:24:55AM -0500, Rik van Riel wrote:
> On Mon, 28 Mar 2005, Andi Kleen wrote:
> 
> > So in short using mempools on receiving is not needed.
> 
> It is, because you have to ensure that the memory that's
> needed to receive network packets isn't tied up receiving
> packets for non-critical sockets, which would leave the
> critical sockets deadlocked.

Again the in socket queue is in no way different from all
the tens of hundreds of limited size queues that make 
up a network. It is quite useless to concentrate on only
one queue in the receiver computer, while all the others still can lose 
packets.

The only way to solve such problems in the TCP/IP model
is to retransmit at the source. This means the TCP write
path needs to be reliable, but receiving does not need to be.

TCP will continuing retransmitting for hours.  If you network
system is so tied up that you cannot receive anything for hours
then yes youre screwed, but I doubt memory reservation will fix
such extreme problems.

-Andi