>> - Is it possible to capture 10-15 second blktrace on your underlying >> physical device. That should give me some idea what's happening. > > Will do, read on. Just realized I missed this one ... Had better done it right away. So here goes. Setup as in first email. 8 Machines, 2 important, 6 not important ones with a throttle of ~10M. group_isolation=1. Each vm dd'ing zeroes. blktrace -d /dev/sdb -w 30 === sdb === CPU 0: 4769 events, 224 KiB data CPU 1: 28079 events, 1317 KiB data CPU 2: 1179 events, 56 KiB data CPU 3: 5529 events, 260 KiB data CPU 4: 295 events, 14 KiB data CPU 5: 649 events, 31 KiB data CPU 6: 185 events, 9 KiB data CPU 7: 180 events, 9 KiB data CPU 8: 17 events, 1 KiB data CPU 9: 12 events, 1 KiB data CPU 10: 6 events, 1 KiB data CPU 11: 55 events, 3 KiB data CPU 12: 28005 events, 1313 KiB data CPU 13: 1542 events, 73 KiB data CPU 14: 4814 events, 226 KiB data CPU 15: 389 events, 19 KiB data CPU 16: 1545 events, 73 KiB data CPU 17: 119 events, 6 KiB data CPU 18: 3019 events, 142 KiB data CPU 19: 62 events, 3 KiB data CPU 20: 800 events, 38 KiB data CPU 21: 17 events, 1 KiB data CPU 22: 243 events, 12 KiB data CPU 23: 1 events, 1 KiB data Total: 81511 events (dropped 0), 3822 KiB data Very constant 296 blocked processes in vmstat during this run. But... apparently no data is written at all (see "bo" column). vmstat 2 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 296 0 125254224 21432 142016 0 0 16 633 181 331 0 0 93 7 0 296 0 125253728 21432 142016 0 0 0 0 17115 33794 0 0 25 75 0 296 0 125254112 21432 142016 0 0 0 0 17084 33721 0 0 25 74 1 296 0 125254352 21440 142012 0 0 0 18 17047 33736 0 0 25 75 0 296 0 125304224 21440 131060 0 0 0 0 17630 33989 0 1 23 76 1 296 0 125306496 21440 130260 0 0 0 0 16810 33401 0 0 20 80 4 296 0 125307208 21440 129856 0 0 0 0 17169 33744 0 0 26 74 0 296 0 125307496 21448 129508 0 0 0 14 17105 33650 0 0 36 64 0 296 0 125307712 21452 129672 0 0 2 1340 17117 33674 0 0 22 78 1 296 0 125307752 21452 129520 0 0 0 0 16875 33438 0 0 29 70 1 296 0 125307776 21452 129520 0 0 0 0 16959 33560 0 0 21 79 1 296 0 125307792 21460 129520 0 0 0 12 16700 33239 0 0 15 85 1 296 0 125307808 21460 129520 0 0 0 0 16750 33274 0 0 25 74 1 296 0 125307808 21460 129520 0 0 0 0 17020 33601 0 0 26 74 1 296 0 125308272 21460 129520 0 0 0 0 17080 33616 0 0 20 80 1 296 0 125308408 21460 129520 0 0 0 0 16428 32972 0 0 42 58 1 296 0 125308016 21460 129524 0 0 0 0 17021 33624 0 0 22 77 Regards Dominik -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list