Re: [PATCH v2] tools/libxl: make default of max event channels dependant on vcpus [and 1 more messages]

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.04.2020 13:00, Ian Jackson wrote:
> Julien Grall writes ("Re: [PATCH v2] tools/libxl: make default of max event 
> channels dependant on vcpus"):
>> There are no correlation between event channels and vCPUs. The number of 
>> event channels only depends on the number of frontend you have in your 
>> guest. So...
>>
>> Hi Ian,
>>
>> On 06/04/2020 11:47, Ian Jackson wrote:
>>> If ARM folks want to have a different formula for the default then
>>> that is of course fine but I wonder whether this might do ARMk more
>>> harm than good in this case.
>>
>> ... 1023 event channels is going to be plenty enough for most of the use 
>> cases.
> 
> OK, thanks for the quick reply.
> 
> So, Jürgen, I think everyone will be happy with this:

I don't think I will be - my prior comment still holds on there not
being any grounds to use a specific OS kernel's (and to be precise
a specific OS kernel version's) requirements for determining
defaults. If there was to be such a dependency, then OS kernel
[variant] should be part of the inputs to such a (set of) formula(s).

Jan

> Ian Jackson writes ("Re: [PATCH v2] tools/libxl: make default of max event 
> channels dependant on vcpus"):
>> I guess you should make two patches 1. duplicate the existing formula
>> (no functional change) 2. change the x86 formula.
>>
>> I would ack the first and be guided by x86 folks for the 2nd.
> 
> Ian.
>