Re: vmscan.c heuristic adjustment for smaller systems

Nick Piggin
2004-04-18T03:38:22Z

Marc Singer wrote:
> On Sat, Apr 17, 2004 at 04:51:51PM -0700, Andrew Morton wrote:
>
>>Marc Singer <elf@buici.com> wrote:
>>
>>>On Sat, Apr 17, 2004 at 04:21:25PM -0700, Andrew Morton wrote:
>>>
>>>>
>>>>How on earth can it take half a minute to list /proc?
>>>
>>>I've watched the vmscan code at work. The memory pressure is so high
>>>that it reclaims mapped pages zealously. The program's code pages are
>>>being evicted frequently.
>>
>>Which tends to imply that the VM is not reclaiming any of that nfs-backed
>>pagecache.
>
>
> I don't think that's the whole story. They question is why.
>

swappiness is pretty arbitrary and unfortunately it means
different things to machines with different sized memory.

Also, once you *have* gone past the reclaim_mapped threshold,
mapped pages aren't really given any preference above
unmapped pages.

I have a small patchset which splits the active list roughly
into mapped and unmapped pages. It might hopefully solve your
problem. Would you give it a try? It is pretty stable here.

Nick