Message-ID: <49D9E53D.5080807@redhat.com>
Date: Mon, 06 Apr 2009 14:19:25 +0300
From: Izik Eidus <ieidus@redhat.com>
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To: Nick Piggin <nickpiggin@yahoo.com.au>
CC: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
       kvm@vger.kernel.org, linux-mm@kvack.org, avi@redhat.com,
       aarcange@redhat.com, chrisw@redhat.com, mtosatti@redhat.com,
       hugh@veritas.com, kamezawa.hiroyu@jp.fujitsu.com
Subject: Re: [PATCH 0/4] ksm - dynamic page sharing driver for linux v2
References: <1238855722-32606-1-git-send-email-ieidus@redhat.com> <200904061704.50052.nickpiggin@yahoo.com.au>
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Nick Piggin wrote:
> On Sunday 05 April 2009 01:35:18 Izik Eidus wrote:
>
>   
>> This driver is very useful for KVM as in cases of runing multiple guests
>> operation system of the same type.
>> (For desktop work loads we have achived more than x2 memory overcommit
>> (more like x3))
>>     
>
> Interesting that it is a desirable workload to have multiple guests each
> running MS office.
>   

This numbers are took from such workload, it is some kind of weird 
script that keep opening Word / Excel and write there like a user...
I think in addition it open internet explorer and enter to random sites...
I can search for the script if wanted...

> I wonder, can windows enter a paravirtualised guest mode for KVM? And can
> you detect page allocation/freeing events?
>   

I Dont know.

>  
>   
>> This driver have found users other than KVM, for example CERN,
>> Fons Rademakers:
>> "on many-core machines we run one large detector simulation program per core.
>> These simulation programs are identical but run each in their own process and
>> need about 2 - 2.5 GB RAM.
>> We typically buy machines with 2GB RAM per core and so have a problem to run
>> one of these programs per core.
>> Of the 2 - 2.5 GB about 700MB is identical data in the form of magnetic field
>> maps, detector geometry, etc.
>> Currently people have been trying to start one program, initialize the geometry
>> and field maps and then fork it N times, to have the data shared.
>> With KSM this would be done automatically by the system so it sounded extremely
>> attractive when Andrea presented it."
>>     
>
> They should use a shared memory segment, or MAP_ANONYMOUS|MAP_SHARED etc.
> Presumably they will probably want to control it to interleave it over
> all numa nodes and use hugepages for it. It would be very little work.
>   

Agree about that, dont know their application to much, i know they had 
problems to do it.

>  
>   
>> I am sending another seires of patchs for kvm kernel and kvm-userspace
>> that would allow users of kvm to test ksm with it.
>> The kvm patchs would apply to Avi git tree.
>>     

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