Re: [Qemu-devel] [PATCH 7/9] pc: acpi: drop not needed intermediate bitmap cpu->found_cpus

[Igor Mammedov]

On Fri, 5 Feb 2016 17:19:50 +0100
Igor Mammedov <address@hidden> wrote:

> On Fri, 5 Feb 2016 13:39:07 -0200
> Eduardo Habkost <address@hidden> wrote:
> 
> > On Thu, Feb 04, 2016 at 12:47:33PM +0100, Igor Mammedov wrote:  
> > > cpu->found_cpus bitmap is used for setting present
> > > flag in CPON AML package at start up. But it takes
> > > a bunch of code to fill bitmap and cloud be simplified
> > > by calling qemu_get_cpu_by_arch_id(apic_id) directly.
> > > 
> > > Hence do so and remove not used anymore bitmap
> > > with related utilities, which saves us ~32LOC
> > > and also would simplify consolidating APCI parts
> > > of CPU hotplug.
> > > 
> > > Signed-off-by: Igor Mammedov <address@hidden>    
> > 
> > This makes the code loops through all smp_cpus CPUs max_cpus
> > times, instead of just looping through the smp_cpus CPUs once.  
> Yep, that looks bad.
> I'll redo it using possible_cpu_arch_ids(), it is a little
> bit bigger refactoring.
I think I'll make bitmap local to build_processor_devices() as it's
needed only for building CPON package, that way it will go along
with related legacy hotplug and won't get in the way of new hotplug.

> 
> > 
> > I'm all for making the code simpler, and there's an upper bound:
> > looking at CPU objects 64k times (because MAX_CPUMASK_BITS is
> > 255). But I want to make sure we agree this is an optimization we
> > want to drop.
> >   
> 
>