From: Alexander Bluhm <bluhm@openbsd.org>
Subject: Re: Add sysctl to disable Nagle's algorithm (RFC 896 - Congestion Control)
To: Job Snijders <job@openbsd.org>
Cc: tech@openbsd.org
Date: Tue, 14 May 2024 17:55:09 +0200

On Mon, May 13, 2024 at 06:41:55PM +0000, Job Snijders wrote:
> Perhaps in the future - after more study & contemplation - we'll to
> change this sysctl's default from 0 to 1?

The common network API is to enable TCP_NODELAY to turn off Nagle's
algorithm.  If we change that default, userland software has to be
written differenty for OpenBSD.

What is the default on FreeBSD and Linux?  If they have switched,
mainstream developers will do it differently.  Then we could also
adapt.

Although for most cases Nagle does not improve performance, it still
depends on the protocol above TCP if that is the case.  I doubt
that a global sysctl can handle this.

How many network programs out there forget to set TCP_NODELAY and
suffer from the old kernel behavior?

bluhm