Date: Mon, 14 Jun 2010 23:10:08 +0530
From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>, kvm <kvm@vger.kernel.org>,
       linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache
 control
Message-ID: <20100614174008.GA5191@balbir.in.ibm.com>
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 <20100610142512.GB5191@balbir.in.ibm.com>
 <1276214852.6437.1427.camel@nimitz>
 <20100611045600.GE5191@balbir.in.ibm.com>
 <4C15E3C8.20407@redhat.com>
 <20100614084810.GT5191@balbir.in.ibm.com>
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* 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
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