Le 06/11/2015 18:28, Simon Hobson a écrit :
I've done no measurements, but my "gut feeling" is that for the servers I
manage (and my OS X laptop), the limiting factor is disk I/O. Thus parallelising service
startup won't help much (if at all) because it just means all the services fire up and
take longer each to start. Eg, (as a simplification) if you have 10 services that take
10s each to start, then they'll take 100s total - starting them in parallel probably
means they'll all take 100s (give or take). All assuming no dependencies of course !
I am booting my servers, say, once per year, but my laptop at
least twice per day. Booting a server takes long, for the reason Rainer
says; I don't care much except when there's an issue I need to debug.
For the laptop I definitely prefer to shut it down before I put it into
my bag to take the metro.
On the servers I have more or less big RAIDs made of
electro-mechanical disks; on my laptop an SSD. Disk access contention
cannot be the same for SSD and electro-mechanical disks, specially when
you only read.
And there is yet other categories of Linux devices: the embedded
and hand-held...
Le 06/11/2015 19:37, KatolaZ a écrit :
Please do not tell the systemd guys that the bios PXE boot takes so
much time to do its work, otherwise they will go head down to replace
it with their own parallel-faster-more-reliable-memory-eating
systemd-PXEbootd.....
Maybe the ultimate reason for Systemd is it was a condition posed
by M$ to provide RedHat on Azure. In which case we talk of virtual
machines, and I expect they don't emulate PXE boot :-)
Didier
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