Didier Kryn <kryn@???> writes:
> Le 05/11/2015 20:05, Rainer Weikusat a écrit :
[...]
>> Worrying about 'starting servers in parallell' only makes sense if
>> there's a real-world situation where this demonstrably makes a relevant
>> difference.
[...]
> Jokes apart, starting daemons in parallel is simply faster when
> you have several cores. I do care booting fast.
I did a litte experiment on this: I booted my 'work computer' via
init=/bin/bash and recorded top -d 0.05 -b output while booting into
multi-user mode via exec init 2, followed by analyzing the resulting
data. The whole procedure took 1minute 12s but this includes the time
needed to start and top the top process.
CPU utilization ((100 - idle) - wait)
-------------------------------------
min 0
max 31
avg 1.74
deviation 2.96
median 0
CPU utilization grouped in 5% buckets
-------------------------------------
0.000-4.000 854 (95.8%)
5.000-9.000 20 (2.2%)
10.000-14.000 9 (1%)
15.000-19.000 1 (0.1%)
20.000-24.000 3 (0.3%)
25.000-29.000 2 (0.2%)
30.000-34.000 2 (0.2%)
Out of 891 samples, 879 had either init, bash or top or a kernel thread
as 'most CPU intensive process', init and bash with 0%. That's 98.65%. The other
twelve were
940 root 20 0 21524 1508 844 S 18.9 0.0 0:00.04 udevd
1060 root 20 0 6404 804 668 D 1.1 0.0 0:00.01 modprobe
812 root 20 0 12768 2556 1916 S 2.5 0.0 0:00.02 startpar
812 root 20 0 12768 2556 1916 S 6.4 0.0 0:00.03 startpar
2838 root 20 0 12772 2560 1916 S 1.0 0.0 0:00.01 startpar
3114 bind 20 0 197m 18m 2080 S 3.0 0.2 0:00.03 named
3147 tunnel 20 0 49164 3496 2780 S 14.8 0.0 0:00.01 ssh
2838 root 20 0 12772 2560 1916 S 14.6 0.0 0:00.03 startpar
2838 root 20 0 12772 2560 1916 S 14.7 0.0 0:00.04 startpar
3301 root 20 0 117m 6048 3996 D 5.9 0.1 0:00.01 apache2
3301 root 20 0 145m 8456 5148 R 17.3 0.1 0:00.04 apache2
3146 tunnel 20 0 49164 3492 2780 S 1.6 0.0 0:00.01 ssh
and these weren't exactly close to each other.
I'm attaching a few graphs showing this but the conclusion is "Whoever
believes parallelization beyond starpar will improve 'booting speed' for
this machine is sadly mistaken".
::
Re: [DNG] Detailed technical treati…
