Re: [Xen-devel] PML (Page Modification Logging) design for Xen

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.03.15 at 07:42, <kai.huang@xxxxxxxxxxxxxxx> wrote:

> 
> On 02/17/2015 06:19 PM, Jan Beulich wrote:
>>>>> On 12.02.15 at 03:39, <kai.huang@xxxxxxxxxxxxxxx> wrote:
>>> On 02/11/2015 07:52 PM, Andrew Cooper wrote:
>>>> On 11/02/15 08:28, Kai Huang wrote:
>>>>> Design
>>>>> ======
>>>>>
>>>>> - PML feature is used globally
>>>>>
>>>>> A new Xen boot parameter, say 'opt_enable_pml', will be introduced to
>>>>> control PML feature detection, and PML feature will only be detected
>>>>> if opt_enable_pml = 1. Once PML feature is detected, it will be used
>>>>> for dirty logging for all domains globally. Currently we don't support
>>>>> to use PML on basis of per-domain as it will require additional
>>>>> control from XL tool.
>>>> Rather than adding in a new top level command line option for an ept
>>>> subfeature, it would be preferable to add an "ept=" option which has
>>>> "pml" as a sub boolean.
>>> Which is good to me, if Jan agrees.
>>>
>>> Jan, which do you prefer here?
>> A single "ept=" option as Andrew suggested.
> Hi Andrew, Jan, Tim,
> 
> Sorry to bring this thread back.
> 
> Regarding to the parameter to control PML, I plan to enable PML by 
> default, in which case would a "ept=no-pml" be more reasonable to 
> disable it manually?

Imo the default should be off at least initially. The command line
option parsing is (and should be) independent of the chosen
default anyway, i.e. overrides in either direction should be
possible.

> Actually by referring to "iommu=" parameter, I would like to do below 
> changes. Is it good to you?

Looks okay.

Jan


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