A method, system and computer program product for dynamically composing processor cores to form logical processors. Processor cores are composable in that the processor cores are dynamically allocated to form a logical processor to handle a change in the operating status. Once a change in the operating status is detected, a mechanism may be triggered to recompose one or more processor cores into a logical processor to handle the change in the operating status. An analysis may be performed as to how one or more processor cores should be recomposed to handle the change in the operating status. After the analysis, the one or more processor cores are recomposed into the logical processor to handle the change in the operating status. By dynamically allocating the processor cores to handle the change in the operating status, performance and power efficiency is improved.