On 07/13/2012 12:47 AM, Raghavendra K T wrote:
Currently Pause Loop Exit (PLE) handler is doing directed yield to a random vcpu on pl-exit. We already have filtering while choosing the candidate to yield_to. This change adds more checks while choosing a candidate to yield_to. On a large vcpu guests, there is a high probability of yielding to the same vcpu who had recently done a pause-loop exit. Such a yield can lead to the vcpu spinning again. The patchset keeps track of the pause loop exit and gives chance to a vcpu which has: (a) Not done pause loop exit at all (probably he is preempted lock-holder) (b) vcpu skipped in last iteration because it did pause loop exit, and probably has become eligible now (next eligible lock holder) This concept also helps in cpu relax interception cases which use same handler.
The patches are tested on x86 only since I don't have access to s390 machine. Please let me know if changes are ok on s390. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
