Re: [PATCH v4 06/11] vpci/header: handle p2m range sets per BAR

[Jan Beulich <jbeulich@suse.com>]

On 19.11.2021 13:13, Oleksandr Andrushchenko wrote:
> On 19.11.21 14:05, Jan Beulich wrote:
>> On 05.11.2021 07:56, Oleksandr Andrushchenko wrote:
>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>>
>>> Instead of handling a single range set, that contains all the memory
>>> regions of all the BARs and ROM, have them per BAR.
>> Iirc Roger did indicate agreement with the spitting. May I nevertheless
>> ask that for posterity you say a word here about the overhead, to make
>> clear this was a conscious decision?
> Sure, but could you please help me with that sentence to please your
> eye? I mean that it was you seeing the overhead while I was not as
> to implement the similar functionality as range sets do I still think we'll
> duplicate range sets at the end of the day.

"Note that rangesets were chosen here despite there being only up to
<N> separate ranges in each set (typically just 1)." Albeit that's
then still lacking a justification for the choice. Ease of
implementation?

As to overhead - did you compare sizeof(struct rangeset) + N *
sizeof(struct range) with just N * sizeof(unsigned long [2])?

Jan