Re: [Xen-devel] Re: [PATCH 1 of 5] xentrace: fix t_info_pages calculation for the default case

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 24/03/2011 15:47, "George Dunlap" <george.dunlap@xxxxxxxxxxxxx> wrote:

> On Wed, 2011-03-23 at 17:54 +0000, Olaf Hering wrote:
>> -    t_info_pages = num_online_cpus() * pages + t_info_first_offset;
>> -    t_info_pages *= sizeof(uint32_t);
>> -    t_info_pages /= PAGE_SIZE;
>> -    if ( t_info_pages % PAGE_SIZE )
>> -        t_info_pages++;
>> +    t_info_bytes = num_online_cpus() * pages + t_info_first_offset;
>> +    t_info_bytes *= sizeof(uint32_t);
>> +    t_info_pages = PFN_UP(t_info_bytes);
> 
> Hmm, still not quite following the spirit of the idea -- that
> t_info_bytes should be bytes, not words (as it is in the first
> instance).  I think I'd prefer making it one assignment:
> 
>     t_info_bytes = ( num_online_cpus() * pages + t_info_first_offset )
>                      * sizeof(uint32_t);
> 
> But if you don't like that, to keep consistent, we should do this:
>     t_info_words = num_online_cpus() * pages + t_info_first_offset;
>     t_info_bytes = t_info_words * sizeof(uint32_t);
>     t_info_pages = PFN_UP(t_info_bytes);
>  
> Then it's really clear when looking at it what the inputs and outputs of
> each line is supposed to be.

I'll clean this up and apply the whole series.

 -- Keir

>  -George
> 
> 
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