'echo NO_NONTASK_CAPACITY > /sys/kernel/debug/sched_features' in both guests. Results: VM1: STA is disabled -- no changes, still little bit bellow expected 90% VM2: STA is enabled -- result is changed, but still bad. Hard to say better or worse. It prefers to stuck at quarters (100% 75% 50% 25%) Output is attached.
Thanks, Alexey On Tue, Oct 20, 2015 at 5:39 AM, Wanpeng Li <kernel...@gmail.com> wrote: > Cc Peterz, > 2015-10-20 5:58 GMT+08:00 Alexey Makhalov <makhal...@gmail.com>: >> >> Hi, >> >> I did benchmarking of scheduler fairness with enabled steal time >> accounting(STA) in KVM. >> And results are really interesting. >> >> Looks like STA provides worse scheduler fairness against disabled STA >> (no-steal-acc cmdline param) >> >> I created benchmark, main idea is: 2 cgroups with cpu.shares >> proportion like 1/9, run identical work in both groups, and expecting >> to get the same proportion of work done – 1/9. Condition – CPU >> overcommit. >> >> On bare metal it is fair +- some percentages of fluctation. >> On KVM with no STA it’s less fair. With STA enabled results are >> ugly! One again – in CPU overcommit situation. >> >> >> Host: ubuntu 14.04, Intel i5 – 2x2 CPUs >> 2 VMs (4 vCPU each) are working in parallel. 2:1 cpu overcommit. >> >> Each VM has running benchmark: >> cgroups cpu.shares proportion is 128/1152 (10%/90%), work – spinning >> in cycle, number of cycles are being counted. > > > Could you try if 'echo NO_NONTASK_CAPACITY > > /sys/kernel/debug/sched_features' in guests works? > > Regards, > Wanpeng Li
90% 28539 75% 31907 76% 30348 75% 43677 75% 29765 63% 30351 74% 28535 70% 29590 65% 31281 87% 29476 75% 29505 75% 29737 75% 29534 75% 29627 89% 30411 75% 29069 74% 29786 74% 29776 74% 29633 74% 29470 74% 29406 90% 30274 90% 29615 96% 30497 100% 29263 100% 29241 100% 29748 100% 29790 99% 29769 74% 66239 52% 118436 50% 117409 50% 118167 50% 118990 50% 38479 48% 29641 50% 29757 50% 29754 50% 29688 50% 29671 50% 29745 50% 29831 50% 29596 50% 29645 50% 29661 50% 29567 50% 29511 50% 29763 50% 29919 51% 28823 51% 29944 50% 29501 50% 29406 50% 29410 49% 29519 51% 30109 49% 29586 49% 29621 49% 29579 43% 80183 49% 118185 49% 113732 45% 29698 25% 29528 24% 30078 36% 29716 32% 28976 43% 77606 19% 131592 0% 39503 12% 29709 25% 29717 24% 29720 25% 29695 25% 29703 25% 29570 25% 29492 25% 29790 25% 29677 25% 29451 25% 29536 25% 29476 25% 29613 24% 30045 24% 30227 37% 52553 43% 29986 50% 29741 49% 30003 50% 29982 35% 29907 39% 30156 48% 30590 66% 58939 --- benchmark was stopped on the first VM. VM1 was in idle from here --- 90% 58977 89% 58952 90% 58945 89% 58945 90% 58948 89% 59001 89% 58966 90% 58966 90% 59005 89% 58998 90% 58998 90% 59010 90% 59028 90% 59070 90% 58558 90% 58948 89% 59080 89% 58601 90% 58385 90% 59003 89% 57695 90% 58843 89% 59104 90% 59006 90% 57110 --- to here --- 97% 30300 100% 29335 100% 29541 100% 29609 100% 29880 100% 29925 100% 29517 100% 29723 100% 28467 99% 29597 100% 29817 100% 29772 100% 29761 100% 29547 100% 29556 100% 29848 100% 29713 100% 29616 100% 29659 100% 29709 100% 29757 100% 29806 100% 30357 100% 29784 100% 29812 100% 29679 100% 29839 100% 29633 100% 29650 100% 29730 100% 29964 100% 29993 100% 29899 100% 29951 100% 29924 100% 29938 100% 29784 100% 30043 100% 29308 99% 30625 95% 29907 99% 29811 100% 29626 100% 30054 100% 29744 100% 29693 100% 30008 100% 29935 100% 29825 100% 29684 100% 30010 100% 30163 93% 51597 89% 58972 89% 58692 90% 57975 100% 27946 100% 29624 100% 30365 98% 30468 99% 30971 100% 30907 100% 28079 100% 30074 100% 29001 100% 30366 99% 29814 100% 30405 97% 29866 100% 29003 100% 28545 100% 29693 100% 30013 100% 28179 100% 28644 100% 30081 100% 28191 100% 31325 100% 30223 100% 29848 100% 30057 100% 29675 100% 29859 100% 28160 100% 29679 100% 29689 100% 29727 100% 29715 100% 30547 100% 29281 100% 29761 100% 29596 100% 29797 100% 29664 100% 29768 100% 29708 100% 29614 100% 29627 100% 30158 100% 29801 100% 28569 100% 29118 100% 30540 100% 29335 100% 29188 99% 30413 100% 29438 100% 28382 100% 29492 100% 28555 100% 29700 99% 30374 75% 29759 75% 29954 75% 29588 75% 29540 75% 29616 75% 29890 75% 29457 75% 29466 75% 29724 74% 29395 74% 29613 75% 29776 75% 29455 75% 29788 75% 29592 75% 29679 75% 29749 75% 29715 75% 29992 75% 29271 73% 30173 74% 29480 75% 29415 75% 28416 75% 29786 75% 29086 75% 29293 75% 29670 75% 29898 75% 29756 75% 29498 75% 29946 75% 29328 75% 29120 75% 29821 75% 29765 75% 29673 75% 29682 75% 29657 74% 30045 75% 29641 75% 29662 75% 29595 75% 29635 75% 29720 73% 30315 75% 29589 75% 29607 75% 29629 75% 29738 75% 30068 72% 28898 75% 26530 74% 30075 73% 29182 74% 28506 73% 28135 74% 29083 75% 29609 73% 27956 74% 28921 74% 29045 74% 29576 74% 29228 74% 29494 74% 29218 73% 27872 74% 29787 74% 29633 68% 32062 98% 31992 98% 32120 90% 32984 98% 32568 98% 32307 97% 32300 98% 32262 99% 30436 94% 30023 96% 32511 99% 31075 99% 30112 100% 29835 100% 30079 100% 29980 100% 29954 100% 29771 100% 29993 100% 29796 100% 29895 100% 29748 100% 29846 100% 29950 100% 29900 100% 29871 100% 29826 100% 29912 100% 29892 100% 29975 100% 29889 100% 29909 100% 29789 100% 30011 100% 29810 100% 29788 100% 30089 100% 30807 100% 29916 100% 29806 100% 29807 98% 30052 100% 29610 100% 29595 100% 30051 100% 29552 99% 30988 100% 28300 100% 30214 100% 31421 100% 31879 100% 30244 100% 30461 100% 26227 100% 32101 100% 31911 100% 28771 100% 29708 100% 28853 100% 29722 100% 29518 100% 29798 100% 28860 100% 29670 100% 30006 100% 30149 100% 29480 100% 29508 100% 29624 100% 29798 100% 30669 100% 29555 100% 29566 100% 29495 100% 29493 100% 29571 100% 29510 100% 29635 100% 29655 100% 29516 100% 29507 100% 29683 100% 29508 100% 29526 100% 29633 100% 29580 100% 29583 100% 29457 100% 29605 100% 29658 100% 29558 100% 29511 100% 29392 100% 29519 100% 29349 100% 29505 100% 39608
