Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control

Balbir Singh
2010-06-14T17:40:08Z

* Avi Kivity <avi@redhat.com> [2010-06-14 18:34:58]:

> On 06/14/2010 06:12 PM, Dave Hansen wrote:
> >On Mon, 2010-06-14 at 14:18 +0530, Balbir Singh wrote:
> >>1. A slab page will not be freed until the entire page is free (all
> >>slabs have been kfree'd so to speak). Normal reclaim will definitely
> >>free this page, but a lot of it depends on how frequently we are
> >>scanning the LRU list and when this page got added.
> >You don't have to be freeing entire slab pages for the reclaim to have
> >been useful. You could just be making space so that _future_
> >allocations fill in the slab holes you just created. You may not be
> >freeing pages, but you're reducing future system pressure.
>
> Depends. If you've evicted something that will be referenced soon,
> you're increasing system pressure.
>

I don't think slab pages care about being referenced soon, they are
either allocated or freed. A page is just a storage unit for the data
structure. A new one can be allocated on demand.

--
Three Cheers,
Balbir