Thanks for the quick reply.

I'm not using the Latency Sensitivity setting, but just reserving CPU for the application to run properly (it's a distributed proprietary application that needs to have CPU reserved to work with decent performances)

I've executed the command with these results:

group-capacity {
cpu-reserved:21000 MHz
cpu-unreserved:298 MHz
mem-reserved:793228 KB
mem-unreserved:125564384 KB

So, means that on my host I can only reserve at maximum 21298 Mhz that is more or less 80% of the total capacity (26400 Mhz)

It's correct to say that Esxi let you reserve a maximum the 80% of the total amount of Mhz?