We replaced Firecracker with QEMU
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We replaced Firecracker with QEMU
1–10 of 156 posts
Re: We replaced Firecracker with QEMU
#2Fly uses Firecracker, and they host long-running processes. I wonder what's their opinion about it.
Re: We replaced Firecracker with QEMU
#3Listen people, Firecracker is NOT A HYPERVISOR. A hypervisor runs right on the hardware. KVM is a hypervisor. Firecracker is a process that controls KVM. If you want to call firecracker (and QEMU, when used in conjunction with KVM) a VMM ("virtual machine monitor") I won't complain. But please please please, we need a word for what KVM and Xen are, and "hypervisor" is the best fit. Stop using that word for a user-level process like Firecracker.
Re: We replaced Firecracker with QEMU
#4I really want VM's to integrate 'smarter' with the host.
For example, if I'm running 5 VM's, there is a good chance that many of the pages are identical. Not only do I want those pages to be deduplicated, but I want them to be zero-copy (ie. not deduplicated after-the-fact by some daemon).
To do that, the guest block cache needs to be integrated with the host block-cache, so that whenever some guest application tries to map data from disk, the host notices that another virtual machine has already caused this data to be loaded, so we can just map the same page of already loaded data into the VM that is asking.
Re: We replaced Firecracker with QEMU
#5> The main issue we've had with QEMU is that it has too many options you need to configure. For instance, enabling your VM to return unused RAM to the host requires at least three challenging tasks
This just works on Hyper-V Linux guests btw. For all the crap MS gets they do some things very right.
Re: We replaced Firecracker with QEMU
#6Fly uses Firecracker, and they host long-running processes. I wonder what's their opinion about it.
I think their usecase makes a lot of sense as their workloads consume a predefined amount of ram. As a customer you rent a VM with a specified amount of memory so fly.io does not care about reclaiming it from a running VM.
Re: We replaced Firecracker with QEMU
#7I really want VM's to integrate 'smarter' with the host. For example, if I'm running 5 VM's, there is a good chance that many of the pages are identical. Not only do I want those pages to be deduplicated, but I want them to be zero-copy (ie. not deduplicated after-the-fact by some daemon). To do that, the guest block cache needs to be integrated with the host block-cache, so that whenever some guest application tries…
This seems like a security issue waiting to happen when you’re running code from different users.
Re: We replaced Firecracker with QEMU
#8I really want VM's to integrate 'smarter' with the host. For example, if I'm running 5 VM's, there is a good chance that many of the pages are identical. Not only do I want those pages to be deduplicated, but I want them to be zero-copy (ie. not deduplicated after-the-fact by some daemon). To do that, the guest block cache needs to be integrated with the host block-cache, so that whenever some guest application tries…
Well that's all nice, but that would also need to be compute-efficient for it to be worthwhile and near-real-time dedupe of memory pages would be a REALLY tough challenge.
Re: We replaced Firecracker with QEMU
#9I really want VM's to integrate 'smarter' with the host. For example, if I'm running 5 VM's, there is a good chance that many of the pages are identical. Not only do I want those pages to be deduplicated, but I want them to be zero-copy (ie. not deduplicated after-the-fact by some daemon). To do that, the guest block cache needs to be integrated with the host block-cache, so that whenever some guest application tries…
I've tried to use virtio-pmem + DAX for the page cache to not be duplicated between the guest and the host. In practice the RAM overhead of virtio-pmem is unacceptable and it doesn't support discard operations at all. So yes a better solution would be needed.
Re: We replaced Firecracker with QEMU
#10No mention of Cloud Hypervisor [1]…perhaps they don’t know about it? It’s based in part on Firecracker and supports free page reporting, virtio-blk-pci, PCI passthrough, and (I believe) discard in virtio-blk.