Re: ~500 megs cached yet 2.6.5 goes into swap hell

Nick Piggin
2004-04-30T13:59:34Z

Rik van Riel wrote:
> On Fri, 30 Apr 2004, Nick Piggin wrote:
>
>> Rik van Riel wrote:
>
>
>> > The basic idea of use-once isn't bad (search for LIRS and
>> > ARC page replacement), however the Linux implementation
>> > doesn't have any of the checks and balances that the
>> > researched replacement algorithms have...
>
>
>> No, use once logic is good in theory I think. Unfortunately
>> our implementation is quite fragile IMO (although it seems
>> to have been "good enough").
>
>
> Hey, that's what I said ;))))
>

Yes. I just thought you might have misunderstood me to
think use once is no good at all.

>> This is what I'm currently doing (on top of a couple of other
>> patches, but you get the idea). I should be able to transform
>> it into a proper use-once logic if I pick up Nikita's inactive
>> list second chance bit.
>
>
> Ummm nope, there just isn't enough info to keep things
> as balanced as ARC/LIRS/CAR(T) can do. No good way to
> auto-tune the sizes of the active and inactive lists.
>

I think perhaps it might be possible. I don't want to
discourage you from looking into more interesting replacement
schemes though. I don't doubt that our basic replacement
can often be suboptimal ;)