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SubjectRe: [patch 10/20] SEQ replacement for anonymous pages
Hi Rik-san

> > > To keep the maximum amount of necessary work reasonable, we scale the
> > > active to inactive ratio with the size of memory, using the formula
> > > active:inactive ratio = sqrt(memory in GB * 10).
>
> > why do you think best formula is sqrt(GB*10)?
> > please tell me if you don't mind.
>
> On a 1GB system, this leads to a ratio of 3 active anon
> pages to 1 inactive anon page, and a maximum inactive
> anon list size of 250MB.
>
> On a 1TB system, this leads to a ratio of 100 active anon
> pages to 1 inactive anon page, and a maximum inactive
> anon list size of 10GB.
>
> The numbers in-between looked reasonable :)

thanks for your kind description.
I think it make sense.

and, please add comment liked blow table if you don't mind.
for take more intuitive description.

total return max
memory value inactive anon
-------------------------------------
10MB 1 5MB
100MB 1 50MB
1GB 3 250MB
10GB 10 0.9GB
100GB 31 3GB
1TB 101 10GB
10TB 320 32GB


> Basically the requirement is that the inactive anon list
> is large enough that pages get a chance to be referenced
> again, but small enough that the maximum amount of work
> the VM needs to do is bounded to something reasonable.
>
> > and i have a bit worry to it works well or not on small systems.
> > because it is indicate 1:1 ratio on less than 100MB memory system.
> > Do you think this viewpoint?
>
> A 1:1 ratio simply means that the inactive anon list is
> the same size as the active anon list. Page replacement
> should still work fine that way.

I'm sold. thanks.


/kosaki





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