Didier Kryn <k...@in2p3.fr> 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".
_______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
