RE: [Xen-ia64-devel] [PATCH] SMP_HOST: Alloc vhpt from domheap

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

First of all, Anthony's previous patch is good enough to check in. This memory 
used for VHPT is allocated from dom heap but doesn't belong to any specific 
domain. In future per VP VHPT options, yes we should account this memory to the 
domain memory size.

Secondly, yes as Alex pointed out, we may redesign the Xenheap size, but it 
looks like we can defer this to some time later. Something in X86 side like m2p 
table may be needed in IA64 side in future but not sure. If we need this one, 
it should be in xenheap that is a relative big memory chunk. On the other side, 
the xenheap is translated by a single TR to save the treasure TLB resource, so 
we can only choose among 16MB, 64MB and 256MB supported by IA64 architecture. 
Probably 16MB is too small :-)  
Eddie



Xu, Anthony wrote:
>> From: Isaku Yamahata
>> Sent: 2006年2月27日 13:18
>> struct domain->max_pages is used for two purposes currently.
>> a) to account pages allocated for a domain.
>>   (by xen/common/page_alloc.c)
>> b) maximal pseudo physical address.
>>   (e.g. lookup_domain_mpa() in xen/arch/ia64/domain.c and others)
>> 
>> This patch breaks b). Somethings needs to be adjusted.
>> Maybe it is needed to add a new member to struct arch_domain for b)
>> and to compensate max_pages at domain construction.
>> 
> Good catch!
> Domain->max_pages should be the number of memory pages allocated to
> domain, for instance, if a domain has 512M memory, the
> domain->max_pages should be 512M/16K. VHPTs are allocated from
> domheap, but not from designated domain due to the first parameter is
> NULL, so domain->max_pages and domain->tot_pages will not be
> impacted. Seems not break a and b. Yes, you can use two variables
> with each representing domain's memory pages and pages used by this
> domain separately, the later includes the former.      
> 
>> 
>> How do you think about accounting pages which is used
>> for struct arch_domain->mm?
>> Please see pgtable_quick_list_alloc() in xen/arch/ia64/xen/xenmis.c.
>> 
> It's the same issue with above, it is better that P2M table is
> allocated from domheap with the first parameter NULL instead of
> xenheap, since you are doing P2M task; you can fix this in the same
> time.   
> 
> 
>> Thanks.
> 
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