[EXTERNAL] Re: ssh wish list?

[Robinson, Herbie]

You aren’t likely to see 10Gb line rate in a single process.  Even without any encryption involved, you will only get between 2 and 5Gb using a single process (at least the last time I tried it).  The problem is you saturate a CPU with protocol interrupt protocol overhead and you can spread a single data stream over multiple CPUs (at least not with TCP or anything else that assumes out of order packets == congestion).  OTOH, if you use GCM on recent hardware where it has been accelerated, the encryption doesn’t add much overhead.

If you are talking multiple processes using accelerated GCM, then it’s possible to hit 10Gb.  I would hazard a guess that 8 cores would be more than enough.

From: openssh-unix-dev <openssh-unix-dev-bounces+herbie.robinson=stratus.com at mindrot.org> On Behalf Of Dave Cottlehuber
Sent: Thursday, October 26, 2023 2:43 PM
To: Chris Rapier <rapier at psc.edu>
Cc: openssh-unix-dev at mindrot.org
Subject: [EXTERNAL] Re: ssh wish list?

[EXTERNAL SENDER: This email originated from outside of Stratus Technologies. Do not click links or open attachments unless you recognize the sender and know the content is safe.]

On Wed, 18 Oct 2023, at 19:13, Chris Rapier wrote:
> Hey all,
>
> So I do some development based on openssh and I'm trying to think of
> some new projects that might extend the functionality, feature set, user
> workflow, performance, etc of ssh.
>
> So open ended question:
>
> Do any of you have a wish list of things you'd like to see in ssh?

Line rate ssh. Like if I have a 10G pipe I should be able to push 10G through without spending significant effort tweaking it for this specific transfer. I know this is partially wishful thinking but I’d like it to be easier.

This might be QUIC or some other UDP layer, or it might be something else entirely.

ssh is my go to tool for shifting almost anything from one place to another, except where I’m limited by single tcp streams.

A+
Dave
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