From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1GShRZ-0002Ab-HC for qemu-devel@nongnu.org; Wed, 27 Sep 2006 17:59:53 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1GShRU-00026I-Li for qemu-devel@nongnu.org; Wed, 27 Sep 2006 17:59:51 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GShRU-000267-ED for qemu-devel@nongnu.org; Wed, 27 Sep 2006 17:59:48 -0400 Received: from [66.249.92.171] (helo=ug-out-1314.google.com) by monty-python.gnu.org with esmtp (Exim 4.52) id 1GShWQ-0005L6-LD for qemu-devel@nongnu.org; Wed, 27 Sep 2006 18:04:54 -0400 Received: by ug-out-1314.google.com with SMTP id j40so97165ugd for ; Wed, 27 Sep 2006 14:59:47 -0700 (PDT) In-Reply-To: <200609272242.00637.paul@codesourcery.com> References: <1ACF2542-5DEE-49B5-8177-5B958911B0F6@gmail.com> <200609272242.00637.paul@codesourcery.com> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: multipart/alternative; boundary=Apple-Mail-4-698555596 Message-Id: From: The MoonSeeker Subject: Re: [Qemu-devel] RAM overcomittment Date: Wed, 27 Sep 2006 23:59:41 +0200 Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Brook Cc: qemu-devel@nongnu.org --Apple-Mail-4-698555596 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed Le 27 sept. 06 =E0 23:41, Paul Brook a =E9crit : > qemu is just like any other application. It is only limited by how =20 > much > virtual memory your OS can provide. ie. if you have sufficient swap =20= > you can > have as many qemu instances using as much memory as you want. > > qemu is currently limits each guest to 2Gb ram. This is independent =20= > of how > much physical memory the host has. > > Note that modern OS (everything except DOS) generally use all =20 > available ram. > Telling qemu to use more memory than you have physical ram is =20 > liable to cause > heavy swapping. Ok but some virtual solution like openVZ allow you run more VM than =20 the memory installed. By example, with openVZ I can create 10 Virtual =20= Machine who have a limite fixe to 200 MB but have guaranteed RAM of =20 20MB. With qemu I need to have 10 X 200MB for VM's + 128 MB host of =20 RAM installed on the work station... I think we can Save ressource because in the most case, the VM's will =20= never use the 200MB. I think it will be a nice if qemu implemented a =20 tool that let use exceed this limitation. I can show you an application domain : For my diploma project, I have to create a network simulator but with =20= these limitation I can't use qemu. Because if would like to simulate =20 20 workstions I need 20 X 128 MB =3D 2560 MB of RAM... + host RAM!!! =20 But in the simulation, the VM's never will use all of ressource.. What do you? Thank you= --Apple-Mail-4-698555596 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1
Le 27 sept. 06 =E0 = 23:41, Paul Brook a =E9crit :

qemu is just like any other = application. It is only limited by how much=A0

virtual memory your OS can provide. ie. = if you have sufficient swap you can=A0

have as many qemu instances using as = much memory as you want.


qemu is currently limits = each guest to 2Gb ram. This is independent of how=A0

much physical memory the host = has.


Note that modern OS (everything except DOS) generally = use all available ram. =A0

Telling qemu to use more memory than = you have physical ram is liable to cause=A0

heavy swapping.

=

Ok but some virtual solution like openVZ = allow you run more VM than the memory installed. By example, with openVZ = I can create 10 Virtual Machine who have a limite fixe to 200 MB but = have guaranteed RAM of 20MB. With qemu I need to have 10 X 200MB for = VM's + 128 MB host of RAM installed on the work station...

I think we can Save = ressource because in the most case, the VM's will never use the 200MB. I = think it will be a nice if qemu implemented a tool that let use=A0exceed = this limitation.

I can show you an = application domain :

For my diploma project, I = have to create a network simulator but with these limitation I can't use = qemu. Because if would like to simulate 20 workstions I need 20 X 128 MB = =3D 2560 MB of RAM... + host RAM!!! But in the simulation, the VM's = never will use all of ressource..

What do you?

Thank = you
= --Apple-Mail-4-698555596--