superpages and kmem on amd64
wojtek at wojtek.tensor.gdynia.pl
Sun May 20 20:22:23 UTC 2012
>>> vm.pmap.pde.demotions: 31
>> No, your conclusion is incorrect. These counts show that 543 superpage
>> mappings were created by promotion.
> OK, that sounds promising. Does "created by promotion" count reflect
> historic / cumulative stats, or is vm.pmap.pde.promotions the actual number
> of superpages active? Or should we subtract vm.pmap.pde.demotions from it to
> get the current value?
correction to my last answer. something is just wrong IMHO
on my 2GB laptop:
[root at wojtek ~]# sysctl -ad vm.pmap.pde
vm.pmap.pde: 2MB page mapping counters
vm.pmap.pde.promotions: 2MB page promotions
vm.pmap.pde.p_failures: 2MB page promotion failures
vm.pmap.pde.mappings: 2MB page mappings
vm.pmap.pde.demotions: 2MB page demotions
[root at wojtek ~]# sysctl -a vm.pmap.pde
from description seems like mappings could be current amount , but both
it's value as well as promotions-demotions gives nonsense.
with 2GB RAM there can not be 3051 or more 2MB pages mapped!
and i - at present - doesn't run many large programs actually only some
xterms and one compiling task.
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