[libvirt] [PATCH 1/2] conf: add disk cache tuning parameters after qemu

[Nikolay Shirokovskiy]

adding cc

On 26.09.2016 13:36, Nikolay Shirokovskiy wrote:
> 
> 
> 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
> 
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