Turning on ECN still causes slow or broken network on linux. Our tcp
is not yet ready for wide spread use of ECN.
This reverts commit 919472741dba6ad0a3f6c2b76d390a02d0e2fdc3.
To further avoid bufferbloat Explicit Congestion Notification (ECN)
should be enabled for both in and outgoing connections. The kernel
default is to enable it when requested for incoming connections, but
not to request it on outgoing connections. This patch enables it for
both.
A long time ago enabling these was causing problems, but these issues
have since been dealt with.
Fixes#9087.
It is redundant because in these cases the values in
`net.ipv4.conf.all.*` take precedence. Also, setting the `default` does
nothing for devices that already exist.
The default of 16 is pretty low, let's bump this to accomodate for more
queued datagrams. This is useful for AF_UNIX/SOCK_DGRAM logging and
sd_notify() sockets as this allows queuing more datagrams before things
start to block, thus improving parallelization and logging performance.
Quoting from Jon Corbet's report of Stephen Hemminger's talk at Linux
Plumbers Conference 2014 (https://lwn.net/Articles/616241/):
[...] So Stephen encouraged everybody to run a command like:
sysctl -w net.core.default_qdisc=fq_codel
That will cause fq_codel to be used for all future connections
[Qdiscs apply to interfaces, not connections. Pointed out by TomH
in the article comments. -- mschmidt] (up to the next reboot).
Unfortunately, the default queuing discipline cannot be changed,
since it will certainly disturb some user's workload somewhere.
Let's have the recommended default in systemd.
Thanks to Dave Täht for advice and the summary at
https://lists.bufferbloat.net/pipermail/cerowrt-devel/2014-October/003701.html
Without this, secondary addresses would get deleted when the primary one is. This is not
the desired behavior when one would like to transition from one address to another in the
same subnet (such as when a new IP address is given over DHCP).
In networkd, when given a new IP over DHCP we will add it, without explicitly removing the
old one first (and hence never have a window without an IP address configured). Assuming the
addresses are in the same subnet, that means that the old address is the primary and the new
address is the secondary one. Once the old address expires, the kernel will drop it. With the
old behavior this means that both addresses would be lost, which is clearly not what we want.
With the new behavior, only the old address is lost, and the new one is promoted to primary.
Reported by Michael Olbrich <m.olbrich@pengutronix.de>
Thomas Hindoe Paaboel Andersen