Re: [Xen-devel] Question on Credit accounting in Credit Scheduler

[George Dunlap <dunlapg@xxxxxxxxx>]

I'd thought of writing a div_round_up() macro that would make this a
bit more clear, something like:

/* Divide x by y, rounding up */
#div_round_up(x, y) (((x)+((y)-1))/(y))

 -George

On Thu, Jul 29, 2010 at 2:35 PM, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
> At 14:21 +0100 on 29 Jul (1280413287), Thomas Pfeuffer wrote:
>> Hello,
>>
>> I have looked through the source code of Credit Scheduler.
>>
>> In csched_acct(), the number of credits a domain gets (i.e credit_fair),
>> is calculated as follows:
>>
>>      credit_fair = ( ( credit_total * sdom->weight) + ( weight_total -1)
>>                   ) / weigth_total
>>
>> But I would expect, that the Credits are calculated by
>>
>>      credit_fair = (credit_total * sdom->weight) / weigth_total
>>
>> Does anybody know, what function the term (weight_total -1) has?
>
> It makes the integer division round up instead of rounding down.
>
> Tim.
>
> --
> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> Principal Software Engineer, XenServer Engineering
> Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)
>
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