Messages in this thread | | | Date | Wed, 19 Dec 2007 08:40:58 -0500 | From | Rik van Riel <> | Subject | Re: [patch 10/20] SEQ replacement for anonymous pages |
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On Wed, 19 Dec 2007 14:17:53 +0900 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> 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 :)
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.
-- "Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." - Brian W. Kernighan
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