Re: [PATCH 0/7] KVM: Kernel-based Virtual Machine

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Alan Cox wrote:
Ar Sul, 2006-10-22 am 10:37 +0200, ysgrifennodd Avi Kivity:
I like this. Since we plan to support multiple vcpus per vm, the fs structure might look like:

Three times the syscall overhead is bad for an emulation very bad

Why? You would usually just call kvm_run(). get/set regs are not needed normally.

for an
emulation of a CPU whose virtualisation is half baked.


Blood rare.  The thing can't even virtualize the first instruction executed.

It's certainly a lot more code though, and requires new syscalls. Since this is a little esoteric does it warrant new syscalls?

I think not - ioctl exists to avoid adding a billion esoteric one user
syscalls. The idea of a VFS sysfs type view of the running vm is great
for tools however so I wouldn't throw it out entirely or see it as ioctl
versus fs.

I still want a separate object per vcpu:


   kvm_fd = open("/dev/kvm")
   for (i = 0; i < n; ++i)
       vcpu_fds[i] = ioctl(kvm_fd, KVM_CREATE_VCPU, i)

so the refcounting doesn't bounce cachelines too much. In effect it's a mini filesystem.

--
error compiling committee.c: too many arguments to function

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