[arch-general] Optimizing boot

Paul Gideon Dann pdgiddie at gmail.com
Wed Apr 30 06:28:52 EDT 2014


On Wednesday 30 Apr 2014 11:08:14 Mike Cloaked wrote:
> Just a comment about boot times. The overall boot performance will depend
> not only on optimising an individual setup, but also is dependent on the
> hardware as well as which boot manager is being used.  So an older laptop
> with a hard drive, using BIOS boot and optimised will still see much longer
> boot time than say a new laptop running a fast i7 processor, with an ssd,
> using UEFI and also optimised.  Certainly I have an old laptop that takes
> around 35 seconds to boot to the login prompt from when the boot manager
> takes over after POST using BIOS legacy boot, but a similarly set up and
> optimised new Haswell i7 laptop, with msata ssd using refind for UEFI boot
> takes about 7 seconds to reach the KDM login prompt. Of course for a
> specific system it may be possible to shave some seconds off the boot time,
> but it will also depend on which server daemons need to be started as well.
> So adding dovecot, an MTA, and maybe a DHCP server all add to the time
> taken to complete the boot process.
> 
> So comparisons of absolute boot times from different machines are difficult
> to interpret.

Since we're on the topic, does anyone have a clue how I can find out why systemd hangs for 
ages when I shut down or reboot? The display server is shut down, I'm placed in a TTY with a 
"shutting-down" message, but then it looks like it's waiting for something that never happens, 
and then I think I see something flash past about a watchdog timeout before it proceeds. If I 
could get rid of that hanging step, it would save me waiting 60 seconds or however long each 
time I reboot (which is infrequently enough that it's only been a mild annoyance so far).

What's the correct way to diagnose this? I don't think systemd-analyze can handle 
shutdown. Could this be an initrd thing?

Paul


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