Messages in this thread | | | Date | Tue, 22 Sep 2009 00:00:48 +1200 | From | Johannes Buchner <> | Subject | Re: Influence of optimization level, preemption and scheduler on boot time |
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On Mon, 21 Sep 2009 13:20:59 +0200 Arjan van de Ven <arjan@infradead.org> wrote:
> On Mon, 21 Sep 2009 23:25:53 +1200 > Johannes Buchner <buchner.johannes@gmx.at> wrote: > > > Hi all. > > > > I measured the kernel (and system) boot times while varying the > > parameters: > > - Optimization level: -Os, -O2 and also -O3 > > - Preemptive model > > - Scheduler: CFQ, Anticipatory, Deadline, Noop > > > > My conclusion was that the optimization level and the preemptive > > model had no significant influence on speed. CFQ let my system boot > > several seconds faster than the other schedulers. > > > > Graphs can be found at: > > http://johannes.jakeapp.com/blog/?p=913 > > > > This conclusion may not be true for all situations, but I found it > > interesting that the optimization level is so irrelevant. > > > > it's interesting to see that the IO scheduler mattered.. > I would think that (s)readahead makes the IO scheduler irrelevant for > boot time...
I did not use (s)readahead though in this measurements. Trying readahead-list with CFQ did not bring me any improvement. Maybe, for the other schedulers, it brings the speed on par with CFQ.
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