Re: [PATCH 0/4] ksm - dynamic page sharing driver for linux v2

[Izik Eidus]

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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