Re: [PATCH] Caches that shrink automatically

[Hans Reiser <reiser@namesys.com>]

Linus Torvalds wrote:

>On Sun, 4 Aug 2002, Rik van Riel wrote:
>  
>
>>>In particular, it is useless for the sub-caches to try to maintain their
>>>own LRU lists and their own accessed bits. But that doesn't mean that
>>>they can _act_ as if they updated their own accessed bits, while really
>>>just telling the page-based thing that that page is active.
>>>      
>>>
>>I'm not sure I agree with this.  For eg. the dcache you will want
>>to reclaim the less used entries on a page even if there are a few
>>very intensely used entries on that page.
>>    
>>
>
>True in theory, but I doubt you will see it very much in practice. 
>
>Most of the time when you want to free dentries, it is because you have a 
>_ton_ of them. 
>
>The fact that some will look cold even if they aren't should not matter 
>that much statistically.
>
>Yah, it's a guess. We can test it.
>
>		Linus
>
>
>
>  
>
Josh tested it.  He posted on it.  I'll have him find his original post 
and repost tomorrow, but summarized in brief, the current dcache 
shrinking/management approach was quite inefficient.  Each active dcache 
entry kept a whole lot of dead ones around.

-- 
Hans