kernel-packages team mailing list archive

[Colin Ian King <1584124@xxxxxxxxxxxxxxxxxx>]

Some data to take into consideration.  I've tested 4 difference configs
(3 laptops, 1 server) of mixed Intel and AMD hardware, comparing the
default powersave/ondemand [1] vs performance

[1] depends on CPU and if intel-pstate is supported

For faster modern Intel CPUs where intel-pstate is supported, there is
minimal difference. Otherwise, performance is a ~3% faster, and all the
gains are in userspace.

See attached spreadsheet.

Tests data was gathered from the average of 25 and average of 50 boots
per CPU scheduler setting. So that's a total of 600 boots in this
dataset across a range of H/W, so I think this data is pretty reliable
data.






** Attachment added: "boot-times-performance-vs-powersave-intel-pstate.ods"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1584124/+attachment/4679093/+files/boot-times-performance-vs-powersave-intel-pstate.ods

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https://bugs.launchpad.net/bugs/1584124

Title:
  revisit /etc/init.d/ondemand

Status in linux package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Triaged

Bug description:
  We've been carrying /etc/init.d/ondemand for many years. We should
  revisit if booting with a kernel that defaults to "ondemand" right
  away is still actually slower than "performance".

  In the short term, systemd should grow a "Type=idle" unit that
  switches to ondemand, to replace the static "1 minute" sleep. This
  will also get rid of the last init.d script in "initscripts" that we
  actually use, and pave the way for dropping the initscripts package.

  In the long term, we could drop it completely if "ondemand" DTRT.

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