[systemd-devel] [PATCH] sysctl.d: default to fq_codel, fight bufferbloat

[Michal Schmidt]

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 (up
    to the next reboot). Unfortunately, the default queuing discipline
    cannot be changed, since it will certainly disturb some user's
    workload somewhere.

So kernel developers know the best default is fq_codel, but won't
change to it in the kernel itself. Instead they expect distros to do it.
Let's have the recommended default in systemd.
---
 sysctl.d/50-default.conf | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sysctl.d/50-default.conf b/sysctl.d/50-default.conf
index 8fc9ab7..f189233 100644
--- a/sysctl.d/50-default.conf
+++ b/sysctl.d/50-default.conf
@@ -25,6 +25,9 @@ net.ipv4.conf.all.accept_source_route = 0
 net.ipv4.conf.default.promote_secondaries = 1
 net.ipv4.conf.all.promote_secondaries = 1
 
+# Fair Queue CoDel packet scheduler to fight bufferbloat
+net.core.default_qdisc = fq_codel
+
 # Enable hard and soft link protection
 fs.protected_hardlinks = 1
 fs.protected_symlinks = 1
-- 
2.1.0