More virtual memory....

Vincent · Joined: 18 Feb 2008 Posts: 20

Is there any way of assigning more memory to the guest than the physical
memory of the host?... maybe some trick ussing vitual memory... I need to
simulate VM with 1.4Gb minimum... (software requierement) but I have only
1gb in the host... The software actually need to run Vista on the guest VM
but it will no use the memory, just need that the system report at least
1.4gb minimun...

--
Mike

Archived from group: microsoft>public>virtualpc

Robert Comer · Joined: 22 Aug 2007 Posts: 447

>Is there any way of assigning more memory to the guest than the physical
>memory of the host?... maybe some trick ussing vitual memory...

No, that's called memory overcommit and Virtual PC doesn't do that.

>I need to
>simulate VM with 1.4Gb minimum... (software requierement) but I have only
>1gb in the host... The software actually need to run Vista on the guest VM
>but it will no use the memory, just need that the system report at least
>1.4gb minimun...

VMWare Workstation can do this, but I suspect it would be so painfully
slow with that large an overcommit.

I'd really suggest testing this on a machine with the right amount of
RAM.

--
Bob Comer

On Sat, 23 Feb 2008 22:00:04 -0500, "Vincent" wrote:

>Is there any way of assigning more memory to the guest than the physical
>memory of the host?... maybe some trick ussing vitual memory... I need to
>simulate VM with 1.4Gb minimum... (software requierement) but I have only
>1gb in the host... The software actually need to run Vista on the guest VM
>but it will no use the memory, just need that the system report at least
>1.4gb minimun...

Vincent · Joined: 18 Feb 2008 Posts: 20

Thanks for your answer Wink

In the "pleistocene" of computers.... I recall some tools to "expand"
memory... that's simulate 16Mb on a 8Mb superslow 386... running Win 3.1.
"Softram" or something like this I guess.... I don't remember if that
utility uses virtual memory or ram compression... I have no idea.... (and
don¡t know if that was memory overcommit also...) Do you know about
something similar at the XP or Vista world? It's probably just a mental
sadism but... you know.... just in case.... Anyway...with memory prices
falling I will buy an extra 1gb ram to go ahead with my tests... (but in a
couples of weeks..)

thanks...

Robert Comer escribió en el mensaje de
noticias 64o1s3pd9mo68s7cqmfoouc5ndfoobfe18@4ax.com...
> >Is there any way of assigning more memory to the guest than the physical
> >memory of the host?... maybe some trick ussing vitual memory...
>
> No, that's called memory overcommit and Virtual PC doesn't do that.
>
> >I need to
> >simulate VM with 1.4Gb minimum... (software requierement) but I have only
> >1gb in the host... The software actually need to run Vista on the guest
VM
> >but it will no use the memory, just need that the system report at least
> >1.4gb minimun...
>
> VMWare Workstation can do this, but I suspect it would be so painfully
> slow with that large an overcommit.
>
> I'd really suggest testing this on a machine with the right amount of
> RAM.
>
> --
> Bob Comer
>
>
>
> On Sat, 23 Feb 2008 22:00:04 -0500, "Vincent" wrote:
>
> >Is there any way of assigning more memory to the guest than the physical
> >memory of the host?... maybe some trick ussing vitual memory... I need
to
> >simulate VM with 1.4Gb minimum... (software requierement) but I have only
> >1gb in the host... The software actually need to run Vista on the guest
VM
> >but it will no use the memory, just need that the system report at least
> >1.4gb minimun...

Robert Comer · Joined: 22 Aug 2007 Posts: 447

>Do you know about
>something similar at the XP or Vista world?

Vista and XP already have such a system in place, as have any Windows
OS after 3.1, but it's not real RAM, it's a system for swapping out
pages of RAM to disk that are not needed at the moment so you can load
in pages of RAM that are. It would be really hard for the host OS to
know what pages in the VM that would not be needed, so something on
top of the host OS in VPC would have to take care of that, adding yet
another layer of virtual memory. So it would be 3 layers, the host,
VPC the app, and then the OS inside the VM and they pretty much fight
each other for resources.

VPC doesn't allow any of it's allocated RAM to be swapped out to disk
though, and it has to allocate real RAM when it starts up, and I
believe the reasons for this is separation of the virtual Machine from
anything the host OS might do with its RAM, and for performance
reasons.

This is all an educated guess on my part, as I really don't know how a
memory overcommit would work with something like VPC, so take it with
a grain of salt, but I do know overcommit on top of virtual memory, is
much, much, slower than having enough RAM to begin with.

--
Bob Comer

On Sun, 24 Feb 2008 02:04:02 -0500, "Vincent" wrote:

>Thanks for your answer Wink

>
>In the "pleistocene" of computers.... I recall some tools to "expand"
>memory... that's simulate 16Mb on a 8Mb superslow 386... running Win 3.1.
>"Softram" or something like this I guess.... I don't remember if that
>utility uses virtual memory or ram compression... I have no idea.... (and
>don¡t know if that was memory overcommit also...) Do you know about
>something similar at the XP or Vista world? It's probably just a mental
>sadism but... you know.... just in case.... Anyway...with memory prices
>falling I will buy an extra 1gb ram to go ahead with my tests... (but in a
>couples of weeks..)
>
>thanks...
>
>
>Robert Comer escribió en el mensaje de
>noticias 64o1s3pd9mo68s7cqmfoouc5ndfoobfe18@4ax.com...
>> >Is there any way of assigning more memory to the guest than the physical
>> >memory of the host?... maybe some trick ussing vitual memory...
>>
>> No, that's called memory overcommit and Virtual PC doesn't do that.
>>
>> >I need to
>> >simulate VM with 1.4Gb minimum... (software requierement) but I have only
>> >1gb in the host... The software actually need to run Vista on the guest
>VM
>> >but it will no use the memory, just need that the system report at least
>> >1.4gb minimun...
>>
>> VMWare Workstation can do this, but I suspect it would be so painfully
>> slow with that large an overcommit.
>>
>> I'd really suggest testing this on a machine with the right amount of
>> RAM.
>>
>> --
>> Bob Comer
>>
>>
>>
>> On Sat, 23 Feb 2008 22:00:04 -0500, "Vincent" wrote:
>>
>> >Is there any way of assigning more memory to the guest than the physical
>> >memory of the host?... maybe some trick ussing vitual memory... I need
>to
>> >simulate VM with 1.4Gb minimum... (software requierement) but I have only
>> >1gb in the host... The software actually need to run Vista on the guest
>VM
>> >but it will no use the memory, just need that the system report at least
>> >1.4gb minimun...
>

Vincent · Joined: 18 Feb 2008 Posts: 20

Thanks

Robert Comer escribió en el mensaje de
noticias acq2s3he4mu7se33fjcpfehrh097tl00f5@4ax.com...
> >Do you know about
> >something similar at the XP or Vista world?
>
> Vista and XP already have such a system in place, as have any Windows
> OS after 3.1, but it's not real RAM, it's a system for swapping out
> pages of RAM to disk that are not needed at the moment so you can load
> in pages of RAM that are. It would be really hard for the host OS to
> know what pages in the VM that would not be needed, so something on
> top of the host OS in VPC would have to take care of that, adding yet
> another layer of virtual memory. So it would be 3 layers, the host,
> VPC the app, and then the OS inside the VM and they pretty much fight
> each other for resources.
>
> VPC doesn't allow any of it's allocated RAM to be swapped out to disk
> though, and it has to allocate real RAM when it starts up, and I
> believe the reasons for this is separation of the virtual Machine from
> anything the host OS might do with its RAM, and for performance
> reasons.
>
> This is all an educated guess on my part, as I really don't know how a
> memory overcommit would work with something like VPC, so take it with
> a grain of salt, but I do know overcommit on top of virtual memory, is
> much, much, slower than having enough RAM to begin with.
>
> --
> Bob Comer
>
>
>
> On Sun, 24 Feb 2008 02:04:02 -0500, "Vincent" wrote:
>
> >Thanks for your answer Wink

> >
> >In the "pleistocene" of computers.... I recall some tools to "expand"
> >memory... that's simulate 16Mb on a 8Mb superslow 386... running Win 3.1.
> >"Softram" or something like this I guess.... I don't remember if that
> >utility uses virtual memory or ram compression... I have no idea.... (and
> >don¡t know if that was memory overcommit also...) Do you know about
> >something similar at the XP or Vista world? It's probably just a mental
> >sadism but... you know.... just in case.... Anyway...with memory prices
> >falling I will buy an extra 1gb ram to go ahead with my tests... (but in
a
> >couples of weeks..)
> >
> >thanks...
> >
> >
> >Robert Comer escribió en el mensaje
de
> >noticias 64o1s3pd9mo68s7cqmfoouc5ndfoobfe18@4ax.com...
> >> >Is there any way of assigning more memory to the guest than the
physical
> >> >memory of the host?... maybe some trick ussing vitual memory...
> >>
> >> No, that's called memory overcommit and Virtual PC doesn't do that.
> >>
> >> >I need to
> >> >simulate VM with 1.4Gb minimum... (software requierement) but I have
only
> >> >1gb in the host... The software actually need to run Vista on the
guest
> >VM
> >> >but it will no use the memory, just need that the system report at
least
> >> >1.4gb minimun...
> >>
> >> VMWare Workstation can do this, but I suspect it would be so painfully
> >> slow with that large an overcommit.
> >>
> >> I'd really suggest testing this on a machine with the right amount of
> >> RAM.
> >>
> >> --
> >> Bob Comer
> >>
> >>
> >>
> >> On Sat, 23 Feb 2008 22:00:04 -0500, "Vincent" wrote:
> >>
> >> >Is there any way of assigning more memory to the guest than the
physical
> >> >memory of the host?... maybe some trick ussing vitual memory... I
need
> >to
> >> >simulate VM with 1.4Gb minimum... (software requierement) but I have
only
> >> >1gb in the host... The software actually need to run Vista on the
guest
> >VM
> >> >but it will no use the memory, just need that the system report at
least
> >> >1.4gb minimun...
> >

Robert Comer · Joined: 22 Aug 2007 Posts: 447

No problem.

--
Bob Comer

On Sun, 24 Feb 2008 09:48:35 -0500, "Vincent" wrote:

>Thanks
>
>Robert Comer escribió en el mensaje de
>noticias acq2s3he4mu7se33fjcpfehrh097tl00f5@4ax.com...
>> >Do you know about
>> >something similar at the XP or Vista world?
>>
>> Vista and XP already have such a system in place, as have any Windows
>> OS after 3.1, but it's not real RAM, it's a system for swapping out
>> pages of RAM to disk that are not needed at the moment so you can load
>> in pages of RAM that are. It would be really hard for the host OS to
>> know what pages in the VM that would not be needed, so something on
>> top of the host OS in VPC would have to take care of that, adding yet
>> another layer of virtual memory. So it would be 3 layers, the host,
>> VPC the app, and then the OS inside the VM and they pretty much fight
>> each other for resources.
>>
>> VPC doesn't allow any of it's allocated RAM to be swapped out to disk
>> though, and it has to allocate real RAM when it starts up, and I
>> believe the reasons for this is separation of the virtual Machine from
>> anything the host OS might do with its RAM, and for performance
>> reasons.
>>
>> This is all an educated guess on my part, as I really don't know how a
>> memory overcommit would work with something like VPC, so take it with
>> a grain of salt, but I do know overcommit on top of virtual memory, is
>> much, much, slower than having enough RAM to begin with.
>>
>> --
>> Bob Comer
>>
>>
>>
>> On Sun, 24 Feb 2008 02:04:02 -0500, "Vincent" wrote:
>>
>> >Thanks for your answer Wink

>> >
>> >In the "pleistocene" of computers.... I recall some tools to "expand"
>> >memory... that's simulate 16Mb on a 8Mb superslow 386... running Win 3.1.
>> >"Softram" or something like this I guess.... I don't remember if that
>> >utility uses virtual memory or ram compression... I have no idea.... (and
>> >don¡t know if that was memory overcommit also...) Do you know about
>> >something similar at the XP or Vista world? It's probably just a mental
>> >sadism but... you know.... just in case.... Anyway...with memory prices
>> >falling I will buy an extra 1gb ram to go ahead with my tests... (but in
>a
>> >couples of weeks..)
>> >
>> >thanks...
>> >
>> >
>> >Robert Comer escribió en el mensaje
>de
>> >noticias 64o1s3pd9mo68s7cqmfoouc5ndfoobfe18@4ax.com...
>> >> >Is there any way of assigning more memory to the guest than the
>physical
>> >> >memory of the host?... maybe some trick ussing vitual memory...
>> >>
>> >> No, that's called memory overcommit and Virtual PC doesn't do that.
>> >>
>> >> >I need to
>> >> >simulate VM with 1.4Gb minimum... (software requierement) but I have
>only
>> >> >1gb in the host... The software actually need to run Vista on the
>guest
>> >VM
>> >> >but it will no use the memory, just need that the system report at
>least
>> >> >1.4gb minimun...
>> >>
>> >> VMWare Workstation can do this, but I suspect it would be so painfully
>> >> slow with that large an overcommit.
>> >>
>> >> I'd really suggest testing this on a machine with the right amount of
>> >> RAM.
>> >>
>> >> --
>> >> Bob Comer
>> >>
>> >>
>> >>
>> >> On Sat, 23 Feb 2008 22:00:04 -0500, "Vincent" wrote:
>> >>
>> >> >Is there any way of assigning more memory to the guest than the
>physical
>> >> >memory of the host?... maybe some trick ussing vitual memory... I
>need
>> >to
>> >> >simulate VM with 1.4Gb minimum... (software requierement) but I have
>only
>> >> >1gb in the host... The software actually need to run Vista on the
>guest
>> >VM
>> >> >but it will no use the memory, just need that the system report at
>least
>> >> >1.4gb minimun...
>> >
>