Re: [Xen-devel] [PATCH v8 2/4] add a domain_tot_pages() helper function

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.01.2020 17:32, Durrant, Paul wrote:
>> -----Original Message-----
>> From: Jan Beulich <jbeulich@xxxxxxxx>
>> Sent: 30 January 2020 16:29
>> To: Durrant, Paul <pdurrant@xxxxxxxxxxxx>
>> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Andrew Cooper
>> <andrew.cooper3@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>; Roger Pau Monné
>> <roger.pau@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxxxxx>; Ian
>> Jackson <ian.jackson@xxxxxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Konrad
>> Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Stefano Stabellini
>> <sstabellini@xxxxxxxxxx>; Tim Deegan <tim@xxxxxxx>
>> Subject: Re: [PATCH v8 2/4] add a domain_tot_pages() helper function
>>
>> On 30.01.2020 15:57, Paul Durrant wrote:
>>> --- a/xen/arch/x86/domain.c
>>> +++ b/xen/arch/x86/domain.c
>>> @@ -218,7 +218,7 @@ void dump_pageframe_info(struct domain *d)
>>>
>>>      printk("Memory pages belonging to domain %u:\n", d->domain_id);
>>>
>>> -    if ( d->tot_pages >= 10 && d->is_dying < DOMDYING_dead )
>>> +    if ( domain_tot_pages(d) >= 10 && d->is_dying < DOMDYING_dead )
>>
>> Before I go any further - are you simply replacing _all_
>> ->tot_pages uses by the new helper?
> 
> Basically, apart from domain_adjust_tot_pages(), yes.
> 
>> In the case here, for
>> example, I don't think this is what we want.
>>
> 
> Why not? I would have thought any 'extra' pages would always be of interest.

Could be hundreds or thousands in the future. As long as it's in
reality just one, perhaps it indeed doesn't matter much. I'll
take a closer look tomorrow, to see if there are other places
where the adjusted count would better not be used. From my
partial audit in the morning I seem to recall that there were
both kinds of situations...

Jan

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