Messages in this thread | | | Date | Fri, 20 Feb 2015 10:39:27 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods |
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On Fri, Feb 20, 2015 at 10:29:34AM -0800, Arjan van de Ven wrote: > On 2/20/2015 10:27 AM, Paul E. McKenney wrote: > >On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > >>>>>>Does it really make a machine boot much faster? Why are people using > >>>>>>synchronous gp primitives if they care about speed? Should we not fix > >>>>>>that instead? > >>>>> > >>>>>The report I heard was that it provided 10-15% faster boot times. > >>>> > >>>>That's not insignificant; got more details? I think we should really > >>>>look at why people are using the sync primitives. > >>> > >>>I must defer to the people who took the exact measurements. > >>> > >>>But yes, once I have that info, I should add it to the commit log. > >> > >>so the two most obvious cases are > >> > >>Registering sysrq keys ... even when the old key code had no handler > >>(have a patch pending for this) > >> > >>registering idle handlers > >>(this is more tricky, it's very obvious abuse but the fix is less clear) > >> > >>there's a few others as well that I'm chasing down... > >>.. but the flip side, prior to running ring 3 code, why NOT do fast expedites? > > > >It would be good to have before-and-after measurements of actual > >boot time. Are these numbers available? > > I'll make you pretty graphs when I get home from collab summit, which > should be later today
Very good, looking forward to seeing them. ;-)
Thanx, Paul
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