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

[Igor Mammedov]

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'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.
>