On 05/08/2012 02:15 AM, Jeremy Fitzhardinge wrote: > On 05/07/2012 06:49 AM, Avi Kivity wrote: > > On 05/07/2012 04:46 PM, Srivatsa Vaddagiri wrote: > >> * Raghavendra K T <[email protected]> [2012-05-07 > >> 19:08:51]: > >> > >>> I 'll get hold of a PLE mc and come up with the numbers soon. but I > >>> 'll expect the improvement around 1-3% as it was in last version. > >> Deferring preemption (when vcpu is holding lock) may give us better than > >> 1-3% > >> results on PLE hardware. Something worth trying IMHO. > > Is the improvement so low, because PLE is interfering with the patch, or > > because PLE already does a good job? > > How does PLE help with ticket scheduling on unlock? I thought it would > just help with the actual spin loops.
PLE yields to up a random vcpu, hoping it is the lock holder. This patchset wakes up the right vcpu. For small vcpu counts the difference is a few bad wakeups (and even a bad wakeup sometimes works, since it can put the spinner to sleep for a bit). I expect that large vcpu counts would show a greater difference. -- error compiling committee.c: too many arguments to function _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
