Re: kvm-37 problem w/ 64-bit division in lapic.c

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Dong, Eddie wrote:
> kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org wrote:
>   
>> Jindrich Makovicka wrote:
>>     
>>> On Mon, 10 Sep 2007 11:49:02 +0200
>>> "Jindrich Makovicka" <makovick-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>>
>>>
>>>       
>>>> On 9/10/07, Dong, Eddie <eddie.dong-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
>>>>
>>>>         
>>>>> div64_32 is enough, does this function exist?
>>>>>
>>>>>           
>>>> afaik, __div64_32 is architecture specific, but do_div() could be
>>>> actually used here. 
>>>>
>>>>         
>>> This version should be faster.
>>>
>>>
>>>       
>> [please don't post patches with extensions like ".diff2", which don't
>> show in the mail reader] 
>>
>>     
>>> -       u32 counter_passed;
>>> +       u64 counter_passed;
>>>         ktime_t passed, now = apic->timer.dev.base->get_time();
>>>         u32 tmcct = apic_get_reg(apic, APIC_TMICT);
>>>
>>> @@ -512,8 +512,8 @@ static u32 apic_get_tmcct(struct kvm_lapic
>>>                 *apic)         } else passed = ktime_sub(now,
>>> apic->timer.last_update); 
>>>
>>> -       counter_passed = div64_64(ktime_to_ns(passed),
>>> -                                 (APIC_BUS_CYCLE_NS *
>>> apic->timer.divide_count)); +       counter_passed =
>>> ktime_to_ns(passed); +       do_div(counter_passed,
>>> APIC_BUS_CYCLE_NS * apic->timer.divide_count);
>>>         tmcct -= counter_passed;
>>>       
>> What if counter_passed overflows?  Sure, that means kvm wasn't
>> scheduled for 4 seconds, but it could happen.
>>
>>
>>     
> It won't happen. see
>  passed = ktime_sub(now, apic->timer.last_update);
>   

Ah, okay.

I'll clean it up later.  I'd like to proceed with the more important 
fixes first.

-- 
error compiling committee.c: too many arguments to function


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