Messages in this thread | | | Date | Fri, 20 Feb 2015 10:27:45 -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 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?
Thanx, Paul
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