From mboxrd@z Thu Jan 1 00:00:00 1970 From: rek2 Subject: Re: Memory under KVM? Date: Sun, 13 Dec 2009 15:23:33 -0500 Message-ID: <4B254D45.40600@binaryfreedom.info> References: <4B22BCE5.7040208@binaryfreedom.info> <200912121337.59872.tfjellstrom@shaw.ca> <4B24BD0D.8070003@redhat.com> <200912130941.47737.tfjellstrom@shaw.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Avi Kivity To: tfjellstrom@shaw.ca Return-path: Received: from mail.binaryfreedom.info ([216.75.30.35]:60654 "HELO libre.binaryfreedom.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751219AbZLMUXg (ORCPT ); Sun, 13 Dec 2009 15:23:36 -0500 In-Reply-To: <200912130941.47737.tfjellstrom@shaw.ca> Sender: kvm-owner@vger.kernel.org List-ID: Hi Thanks for the responses, but look: PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin /usr/bin/kvm -S -M pc-0.11 -m 1024 -smp 1 -name vm_hsci -uuid 52ed4c7c-65e4-325e-0f96-87a5be6d854c -monitor unix:/var/run/libvirt/qemu/vm_hsci.monitor,server,nowait -boot c -drive file=/var/kvm_images/vm_hsci.img,if=virtio,index=0,boot=on -net nic,macaddr=00:16:36:5b:c4:e2,vlan=0,name=nic.0 -net tap,fd=16,vlan=0,name=tap.0 -serial pty -parallel none -usb -vnc 127.0.0.1:0 -k en-us -vga cirrus -soundhw es1370 I have -m 1ith 1024 right? but if I do a top: 1214m 364m 3360 S 0 4.5 46:55.24 kvm so is clearly above -m what could be the issue? Thanks is using 1214 at this moment sometimes it goes up a lot more.. On 12/13/09 11:41 AM, Thomas Fjellstrom wrote: > On Sun December 13 2009, Avi Kivity wrote: > >> On 12/12/2009 10:37 PM, Thomas Fjellstrom wrote: >> >>> I have the opposite happen, when a VM is started, RES is usually lower >>> than -m, which I find slightly odd. But makes sense if qemu/kvm don't >>> actually allocate memory from the host till its requested the first >>> time >>> >> That is the case. >> >> >>> (if only it >>> would return some of it afterwards, it would be even better). >>> >> Use the balloon driver to return memory to the host. >> > Will it actually just free the memory and leave the total memory size in the > VM alone? Last I checked it would just decrease the total memory size, which > isn't that useful. Sometimes it needs more ram, so its given 512M ram, but > most of the time can live on 100M or so. > > >>> I just fully shut down and restarted on of my vms, which is set to use >>> 128-256 MB ram max. RES is like 72MB on start, and VIRT is 454M. RES >>> generally gets up around 120MB ram when its doing something. >>> >>> One thing I do find a little odd is one of my VMs which is allocated >>> 512MB ram, has a VIRT of 826MB ram. I didn't realize that qemu had so >>> many lib dependencies. >>> >> It's not just libraries, it's mostly glibc malloc() allocating huge >> pools per thread, as well as large thread stacks. >> >> >>> Due to kvm not supporting giving memory back, besides by >>> swapping large portions of unused guest ram, my host currently has over >>> 1G used swap. Not particularly happy with that, but it doesn't seem to >>> effect performance too much (except that it generally likes to swap >>> host processes first, guest performance is decent, but host, not so >>> much). >>> >> The Linux vm prefers anonymous memory, so guests do get an advantage. >> >> > I think the only thing I'd like to have now is automatic memory return, much > like vmware server has. It doesn't change what the guest VM sees, it just > flushes the unused ram back to the host. > >