Re: Minutes from Feb 21 LSE Call

Martin J. Bligh
2003-02-26T05:51:57Z

>>> My impression thus far is that the anonymous case has not been pressing
>>> with respect to space consumption or cpu time once the file-backed code
>>> is in place, though if it resurfaces as a serious concern the anonymous
>>> rework can be pursued (along with other things).
>
> On Wed, Feb 26, 2003 at 02:24:18AM -0300, Rik van Riel wrote:
>> ... but making the anonymous pages use an object based
>> scheme probably will make things too expensive.
>> IIRC the object based reverse map patches by bcrl and
>> davem both failed on the complexities needed to deal
>> with anonymous pages.
>> My instinct is that a hybrid system will work well in
>> most cases and the worst case with mapped files won't
>> be too bad.
>
> The boxen I'm supposed to babysit need a high degree of resource
> consciousness wrt. lowmem allocations, so there is a clear voice

It seemed, at least on the simple kernel compile tests that I did, that all
the long chains are not anonymous. It killed 95% of the space issue, which
given the simplicity of the patch was pretty damned stunning. Yes, there's
a pointer per page I guess we could kill in the struct page itself, but I
think you already have a better method for killing mem_map bloat ;-)

M.