[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: next->vcpu_dirty_cpumask checking at the top of context_switch()
On 17/04/2009 14:58, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: >>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 04/16/09 6:00 PM >>> >> How big NR_CPUS are we talking about? Is the overhead measurable, or is this >> a premature micro-optimisation? > > We're shipping Xen in SLE11 with NR_CPUS=255, and I'm convinced we'll be asked > to up this further in the service packs. > > Also, micro-optimization reads for me like I was aiming at a performance > issue, but the goal really just is to get the use of stack space down (and in > particular, make it as independent as possible from configuration settings). Well, I'm not against it, at least if it's a reasonably straightforward patch. Any untangling of cpus_empty() logic should be a separate patch though. And that should mean that the patch to convert from pass-by-value to pass-by-pointer is nice and trivial. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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