On 16 October 2014 21:31, Pranith Kumar <bobby.pr...@gmail.com> wrote: > I am trying to gather some instruction execution statistics of a > multi-threaded program by adding some counters in TCG. > > I've learnt that multi-threaded execution is not supported in user > mode and in system mode with TCG. Is KVM the only mode which supports > multi-threaded execution? Or is the support related to SMP mode?
TCG system mode supports running multi-threaded guests fine, and we support both single CPU and multiple CPU guest configs. What we don't do is make use of multiple host threads when we're doing this, so we emulate a 4 core system by running guest instructions for each core in turn within a single host thread. This is a performance limitation, not a functional one. (If you care largely about performance then for TCG you are best off specifying a single guest CPU config; multiple guest CPUs will run slower, not faster.) thanks -- PMM