Il 26/02/2014 16:14, Christian Borntraeger ha scritto:
Paolo,here is the reworked yield heuristics series against kvm/queue with your suggested changes. Attached is a minimized testcase that reproduces the performance win (runtime 0:50 instead of 1:00). The constants and the setup seem a bit artificial but these seem to reproduce the problem on my test system: as soon as there is contention from other guests the patch improves the runtime of belows testcase. The original test had 8 competing guests with 4 cpus, I simplified that a bit to have one big guest as cpu stealer. host 20 cpus GUEST1 (20vCPUS) GUEST2(40vCPUS) runs the test all 40 CPUs cpu bound The testcase stresses the IPC system call, since that creates a lot of diag44 exits on s390 if contended. Some other spinlock tests like fio on guest tmpfs seem to be unaffected. Please consider for kvm/queue. If you have some performance tests a regression run on x86 is welcome.
Yes, will apply as soon as kvm/queue moves to kvm/next (1 hour or so). Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
