[Qemu-discuss] Skipping Option Rom kvmcapic.bin
Target: x86 PC How can i skip loading this option rom (kvmvapic.bin)? Is there any option in qemu or SEABios?
[Qemu-discuss] QEMU singlestep
Hello, I've been using QEMU in user mode to run an executable with debug mode and I've noticed that the number of assembly instructions differs from one runtime to another, even for a trivial "hello world". Is there an explanation for this? qemu-aarch64 -singlestep -d in_asm hello_world.exe has fewer instructions than qemu-aarch64 -d in_asm hello_world.exe Thanks, Radu
Re: [Qemu-discuss] Live migration of VM
IMO although likely possible, unlikely to ever be implemented unless someone could describe a scenario common enough to warrant the effort. The concepts behind doing a live migration exist and are implemented in a few technologies (stability varies). If the code is closed though, it may limit who might be able to build a solution that needs this functionality. But, the principles are well known, ie. freeze a snapshot, copy it (or its equivalent), track changes since the snapshot, apply changes until the source and target are consistent whereupon you can then execute switching over. For a distro (OS) that runs on both the source and target are well known, ie what is required for each platform and what is comparable to what. Assuming no special platform specific tuning, generic deployments that mirror source and target are probably quite feasible, but the question is if there are enough people who would want/need to do such a thing. IMO, Tony On Tue, May 27, 2014 at 7:26 AM, Dale R. Worley wrote: >> From: On Behalf Of Prashant Upadhyaya >> Sent: Friday, May 23, 2014 11:49 AM >> To: qemu-discuss@nongnu.org >> Subject: [Qemu-discuss] Live migration of VM >> >> Is it possible to live migrate a VM (emulating AMD) running on >> native AMD to a machine running native ARM and back with QEMU ? > > It seems unlikely. How would one implement such a thing? You'd have > to somehow convert a memory image full of AMD instructions into a > memory image full of ARM instructions but still represents the same > state of the same computation. > > Dale >
Re: [Qemu-discuss] Live migration of VM
On 5/23/2014 8:19 AM, Prashant Upadhyaya wrote: Hi, Is it possible to live migrate a VM (emulating AMD) running on native AMD to a machine running native ARM and back with QEMU ? I believe a clarification is needed here. What is it you want to do: A) Migrate the VM from qemu-system-x86_64 software emulating an AMD64 guest on an AMD64 host to qemu-system-x86_64 software emulating the same AMD64 guest on an ARM host. B) Migrate the VM from qemu-system-x86_64 KVM emulating an AMD64 guest on an AMD64 host to qemu-system-x86_64 software emulating the same AMD64 guest on an ARM host C) Migrate the VM from qemu-system-x86_64 emulating an AMD64 guest on an AMD64 host to qemu-system-arm emulating an ARM guest on an ARM host. C) Is mostly impossible, because the Guest memory needs to contain completely different code when the virtual machine suddenly swaps its (virtual) CPU from AMD64 to ARM. A) Might be possible, unless there is some oddity in the qemu code which transmits the virtual machine state differently depending on the Host architecture. B) Might be more difficult, if the qemu code transmits KVM virtual machine state differently from equivalent software emulated virtual machine state. Enjoy Jakob -- Jakob Bohm, CIO, Partner, WiseMo A/S. http://www.wisemo.com Transformervej 29, 2730 Herlev, Denmark. Direct +45 31 13 16 10 This public discussion message is non-binding and may contain errors. WiseMo - Remote Service Management for PCs, Phones and Embedded
Re: [Qemu-discuss] Live migration of VM
> From: Prashant Upadhyaya > Is it possible to live migrate a VM (emulating AMD) running on > native AMD to a machine running native ARM and back with QEMU? I believe I was incorrect in my previous answer. Given that Qemu can support a different guest architecture than the host archicture (via TCG), it seems that live-migrating from one host architecture to a different host architecture isn't much more difficult than live-migrating between two hosts with the same architecture. (This is assuming that the emulated peripherals are exactly the same, etc.) And there does seem to be a migration facility in Qemu, though the documentation I could find for it is very thin. Dale
[Qemu-discuss] Disk Performance
Big picture, I'm working on getting an openstack deployment going using ceph-backed volumes, but I'm running into really poor disk performance, so I'm in the process of simplifying things to isolate exactly where the problem lies. The machines I'm using are HP Proliant DL160 G6 machines with 72GB of RAM. All the hardware virtualization features are turned on. Host OS is Ubuntu 14.04, using deadline IO scheduler. I've run a variety of benchmarks to make sure the disks are working right, and they seem to be. Everything indicates bare metal write speeds to a single disk in the ~100MB/s ballpark. Some tests report as high as 120MB/s. To try to isolate the problem I've done some testing with a very simple [1] qemu invocation on one of the host machines. Inside that VM, I get about 50MB/s write throughput. I've tested with both qemu 2.0 and 1.7 and gotten similar results. For quick testing I'm using a simple dd command [2] to get a sense of where things lie. This has consistently produced results near what more intensive synthetic benchmarks (iozone and dbench) produced. I understand that I should be expecting closer to 80% of bare metal performance. It seems that this would be the first place to focus, to understand why things aren't going well. When running on a ceph-backed volume, I get closer to 15MB/s using the same tests, and have as much as 50% iowait. Typical operations that take seconds on bare metal take tens of seconds, or minutes in a VM. This problem actually drove me to look at things with strace, and I'm finding streams of FSYNC and PSELECT6 timeouts while the processes are running. More direct tests of ceph performance are able to saturate the nic, pushing about 90MB/s. I have ganglia installed on the host machines, and when I am running tests from within a vm ,the network throughput seems to be getting artificially capped. Rather than the more "spiky" graph produced by the direct ceph tests, I get a perfectly flat horizontal line at 10 or 20MB/s. Any and all suggestions would be appreciated, especially if someone has a similar deployment that I could compare notes with. QH 1 - My testing qemu invocation: qemu-system-x86_64 -cpu host -m 2G -display vnc=0.0.0.0:1 -enable-kvm -vga std -rtc base=utc -drive if=none,id=blk0,cache=none,aio=native,file=/root/cirros.raw -device virtio-blk-pci,drive=blk0,id=blk0 2 - simple dd performance test: time dd if=/dev/zero of=deleteme.bin bs=20M count=256
Re: [Qemu-discuss] Live migration of VM
Hi, Case A and B are what I am looking for. I believe B is more likely for practical usecases for speed of guest execution. I saw this news from 2008 and thought that years have passed, so this must be possible now. But looks like this still hasn't matured. http://beta.slashdot.org/story/109745 Would love to hear comments on the above story from back then. Regards -Prashant -Original Message- From: qemu-discuss-bounces+prashant.upadhyaya=aricent@nongnu.org [mailto:qemu-discuss-bounces+prashant.upadhyaya=aricent@nongnu.org] On Behalf Of Jakob Bohm Sent: Wednesday, May 28, 2014 11:02 PM To: qemu-discuss@nongnu.org Subject: Re: [Qemu-discuss] Live migration of VM On 5/23/2014 8:19 AM, Prashant Upadhyaya wrote: > Hi, > > Is it possible to live migrate a VM (emulating AMD) running on native > AMD to a machine running native ARM and back with QEMU ? > > I believe a clarification is needed here. What is it you want to do: A) Migrate the VM from qemu-system-x86_64 software emulating an AMD64 guest on an AMD64 host to qemu-system-x86_64 software emulating the same AMD64 guest on an ARM host. B) Migrate the VM from qemu-system-x86_64 KVM emulating an AMD64 guest on an AMD64 host to qemu-system-x86_64 software emulating the same AMD64 guest on an ARM host C) Migrate the VM from qemu-system-x86_64 emulating an AMD64 guest on an AMD64 host to qemu-system-arm emulating an ARM guest on an ARM host. C) Is mostly impossible, because the Guest memory needs to contain completely different code when the virtual machine suddenly swaps its (virtual) CPU from AMD64 to ARM. A) Might be possible, unless there is some oddity in the qemu code which transmits the virtual machine state differently depending on the Host architecture. B) Might be more difficult, if the qemu code transmits KVM virtual machine state differently from equivalent software emulated virtual machine state. Enjoy Jakob -- Jakob Bohm, CIO, Partner, WiseMo A/S. http://www.wisemo.com Transformervej 29, 2730 Herlev, Denmark. Direct +45 31 13 16 10 This public discussion message is non-binding and may contain errors. WiseMo - Remote Service Management for PCs, Phones and Embedded "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error, please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus."
