Re: RFC: Noreclaim with "Keep Mlocked Pages off the LRU"

[Rik van Riel <riel@redhat.com>]

Christoph Lameter wrote:
> On Wed, 29 Aug 2007, Lee Schermerhorn wrote:
> 
>>> I think that is the right approach. Do not forget that ramfs and other 
>>> ram based filesystems create unmapped unreclaimable pages.
>> They don't go on the LRU lists now, do they?  The primary function of
>> the noreclaim infrastructure is to hide non-reclaimable pages that would
>> otherwise go on the [in]active lists from vmscan.  So, if pages used by
>> the ram base file systems don't go onto the LRU, we probably don't need
>> to put them on the noreclaim list which is conceptually another LRU
>> list.
> 
> They do go into the LRU. When attempts are made to write them out they are 
> put back onto the active lists via a strange return code 
> AOP_WRITEPAGE_ACTIVATE. So they circle round and round and round...
> 
>>> Right. I posted a patch a week ago that generalized LRU handling and would 
>>> allow the adding of additional lists as needed by such an approach.
>> Which one was that? 
> 
> This one
> 
> [RECLAIM] Use an indexed array for active/inactive variables
> 
> Currently we are defining explicit variables for the inactive and active
> list. An indexed array can be more generic and avoid repeating similar
> code in several places in the reclaim code.

I like it.  This will make the code that has separate lists
for anonymous (and other swap backed) pages a lot nicer.

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