Re: [libvirt] [PATCH 1/2] conf: add disk cache tuning parameters after qemu
On 26.09.2016 13:04, Peter Krempa wrote:
On Mon, Sep 26, 2016 at 12:15:42 +0300, Nikolay Shirokovskiy wrote:
> On 26.09.2016 12:01, Peter Krempa wrote:
[...]
> Sorry, I forget to write down the motivation.
>
> Internally qemu uses 3 orthogonal flags to configure disk cache. They
> are exposed in interface too quite long time ago (29c4e2b). All-in-one
> cache parameter that libvirt uses now do not provide all possible
> values (5 vs 8). For example absent combination of direct + no flush (no sync)
> is useful to speed up tests.
Well, if there are useful combinations we can add them to the existing
cache setting.
> So I decided to provide new possibilities just as qemu does - keep
> old parameter and use new ones to tune over.
I don't think this is a good idea at all. It's very qemu specific and
can be mapped to existing elements.
Peter
Well up until now libvirt cache settings are exactly the same as the qemu ones. I thought
it would be inconsistent to intordocuce new name and then map internallly to
qemu. Another point is that these 3 parameters are probably not that qemu specific.
Nikolay