Controlling exhaust gas recirculation in a turbocharged engine system

A method of controlling exhaust gas recirculation (EGR) in a turbocharged engine system (10) including an engine (12), an induction subsystem (14) in upstream communication with the engine (12), an exhaust subsystem (16) in downstream communication with the engine (12), a high pressure EGR path (46) between the exhaust and induction subsystems (14) upstream of a turbocharger turbine (38) and downstream of a turbocharger compressor (28), and a low pressure EGR path (48) between the exhaust and induction subsystems (14) downstream of the turbocharger turbine (38) and upstream of the turbocharger compressor (48). A target total EGR fraction for compliance with exhaust emissions criteria is determined, then a target HP/LP EGR ratio is determined to optimize other engine system criteria within the constraints of the determined target total EGR fraction.