| 2015-10-23 11:00:41 |
Tim Bell |
description |
QCOW2 performance can be significantly improved by setting the l2-cache-size parameter for large qcow2 based storage (such as images and ephemeral drives) (see https://events.linuxfoundation.org/sites/events/files/slides/p0.pp_.pdf).
Adding support for this optional parameter (which adds [...]-drive file=hd.qcow2,l2-cache-size=2097152 to the qemu CLI) would allow operators and/or users to configure a more tuned configuration.
A simple simple implementation where a default value could be set in nova.conf would already give an improved flexibility. Ideally, this could also be specified as an image or flavor property so that only large drives would need to allocate the additional memory.
I could not locate an option such as this in the OpenStack versions up to Liberty. |
QCOW2 performance can be significantly improved by setting the l2-cache-size parameter for large qcow2 based storage (such as images and ephemeral drives) (see https://events.linuxfoundation.org/sites/events/files/slides/p0.pp_.pdf).
Adding support for this optional parameter (which adds [...]-drive file=hd.qcow2,l2-cache-size=2097152 to the qemu CLI) would allow operators and/or users to configure a more tuned configuration.
A simple implementation where a default value could be set in nova.conf would already give an improved flexibility. A formula could also be used with a factor relative to the size of the storage.
Ideally, this could also be specified as an image or flavor property so that only large drives would need to allocate the additional memory.
I could not locate an option such as this in the OpenStack versions up to Liberty. |
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