[libvirt-users] Setting elevator=noop in the guest necessary?

[Johannes Kastl]

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Hi everyone,

I found an article about libvirt, and one thing that I have not seen
anywhere else:

> IMPORTANT: If you boot a Linux VM, you might want to add 
> “elevator=noop” to your Linux boot command line to force the disk 
> scheduler to let the host machine handle the disk writes 
> reorganisations (like tunnelling tcp over tcp, it is bad to have
> two schedulers trying to do each other’s job). For example, on
> GRUB2 on Debian, you have to append “elevator=noop” after
> GRUB_CMDLINE_LINUX in /etc/default/grub.
(from
http://blog.normation.com/en/2012/03/09/a-guide-to-the-everyday-use-of-libvirt-and-kvm/)

Is this necessary? Or is this even a good idea? Is this outdated? Or
does it depend on the kind of hypervisor (XEN, KVM,...)?

The few qemu/KVM-machines I have tested did work fine without this,
although at this point I just set them up and did a few program
installations, no real 'workload'.

Thanks in advance.

Regards,
Johannes
- -- 
...Unix, MS-DOS, and Windows NT (also known as the Good, the Bad, and
the Ugly).
(Matt Welsh)
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