Bug#890343: systemd: Debian could use the fq_codel network queuing algorithm by default

[Laurent Bonnaud]

Package: systemd 
Version: 237-2 
Severity: normal


Dear Maintainer,

by default Debian uses the pfifo_fast network queuing algorithm:

# tc -s qdisc show
[...]
qdisc pfifo_fast 0: dev eth0 root refcnt 2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
 Sent 413728102 bytes 475015 pkt (dropped 0, overlimits 0 requeues 785)
 backlog 0b 0p requeues 785

The systemd source package contains this file:

  ./systemd-237/sysctl.d/50-default.conf:net.core.default_qdisc = fq_codel

whose purpose is to set the default queuing algorithm to fq_codel.  According to the NEWS file, this is a better alternative:

        * The default sysctl.d/ snippets will now set:

                net.core.default_qdisc = fq_codel

          This selects Fair Queuing Controlled Delay as the default
          queuing discipline for network interfaces. fq_codel helps
          fight the network bufferbloat problem. It is believed to be
          a good default with no tuning required for most workloads.
          Downstream distributions may override this choice. On 10Gbit
          servers that do not do forwarding, "fq" may perform better.
          Systems without a good clocksource should use "pfifo_fast".

However the 50-default.conf file is not in the Debian binary package.
Is this intentional or an omission?
Could it be possible to enable fq_codel by default?


-- Package-specific info:

-- System Information:
Debian Release: buster/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (1, 'experimental-debug'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 4.14.0-3-rt-amd64 (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd depends on:
ii  adduser          3.117
ii  libacl1          2.2.52-3+b1
ii  libapparmor1     2.12-2
ii  libaudit1        1:2.8.2-1
ii  libblkid1        2.31.1-0.1
ii  libc6            2.27-0experimental0
ii  libcap2          1:2.25-1.2
ii  libcryptsetup12  2:2.0.1-1
ii  libgcrypt20      1.8.2-1
ii  libgpg-error0    1.27-6
ii  libidn11         1.33-2.1
ii  libip4tc0        1.6.2-1
ii  libkmod2         25-1
ii  liblz4-1         0.0~r131-2+b1
ii  liblzma5         5.2.2-1.3
ii  libmount1        2.31.1-0.1
ii  libpam0g         1.1.8-3.7
ii  libseccomp2      2.3.1-2.1
ii  libselinux1      2.7-2+b1
ii  libsystemd0      237-2
ii  mount            2.31.1-0.1
ii  procps           2:3.3.12-4
ii  util-linux       2.31.1-0.1

Versions of packages systemd recommends:
ii  dbus            1.13.0-1
ii  libpam-systemd  237-2

Versions of packages systemd suggests:
ii  policykit-1        0.113-6
pn  systemd-container  <none>

Versions of packages systemd is related to:
pn  dracut           <none>
ii  initramfs-tools  0.130
ii  udev             237-2

-- 
Laurent.