Re: [Minios-devel] [UNIKRAFT PATCH v2] plat/*: Configure timer interrupt frequency

[Costin Lupu <costin.lup@xxxxxxxxx>]

On 10/5/18 12:24 PM, Florian Schmidt wrote:
> Hi Costin,
> 
> let me give a quick answer:
> 
> On 10/02/2018 09:16 AM, Costin Lupu wrote:
>> I find allowing users the freedom to set any frequency they like to have
>> 2 disadvantages:
>>
>> 1. The tick frequency should be chosen based on a prior analysis
>> depending on the application. An integer field would allow users to set
>> any frequency they want whether they know what they're doing or not. I
>> find this level of freedom dangerous here.
> 
> Well, that's up to the developer, I think. I'm for the freedom to shoot
> yourself in the foot if you think you know better what to set here.
> 
> 
>> 2. A given frequency value may not be supported by the underlying timers
>> and therefore it would either have no effect (e.g. being ignored) or
>> generate an incorrect behavior.
> 
> That should be captured by an error-handling mechanism, right? Through a
> CRIT warning or worst case crash when a settings doesn't work. Or are
> you saying that some timers silently ignore unsupported settings without
> giving any way to figure out whether a setting will work or not?
> 

In deed, an error handling mechanism should be introduced in this case.
But this would only add more complexity and should be according to each
supported timer. Please keep in mind that there is no standard way of
configuring timers and the set of accepted interrupt frequency values
may differ.

> 
>> Now regarding the number of options, two should be enough for making the
>> case for how we can configure the timer. Please feel free to amend this
>> patch or to submit another one for extending the number of options.
> 
> I might do that, but I'd prefer to have some additional input from
> others first.
> 
> Cheers,
> Florian

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