I'm seeing a regression with this kernel on dawson-i nuc (NUC7i3DNHE) on the clocktest test in checkbox. This is a test that checks for cpu clock jitter, and I retried it multiple times and it is very reproducible. I also reverted to the kernel in stable and failed to reproduce it there. You can find the code for this test at https://git.launchpad.net/plainbox-provider-checkbox/tree/src/clocktest.c or you can also install the checkbox snap (uc18/stable) and run "checkbox.checkbox-cli run '.*clocktest.*'" to run it from the snap. When the test passed for me (on the previous kernel) the output looked like this: Testing for clock jitter on 4 cpus PASSED: largest jitter seen was 0.000167 Testing clock direction for 5 minutes... PASSED: Iteration 0 delta: 0.000229 PASSED: Iteration 1 delta: 0.000259 PASSED: Iteration 2 delta: 0.000242 PASSED: Iteration 3 delta: 0.000235 PASSED: Iteration 4 delta: 0.000247 clock direction test: sleeptime 60 sec per iteration, failed iterations: 0 When it failed on this kernel, it took much longer to run. This was the output: Testing for clock jitter on 4 cpus ERROR: jitter = 0.254654 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 50, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236886 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 148, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236831 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 181, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.339615 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 197, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236866 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 215, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236817 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 522, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254743 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 549, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254881 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 617, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254600 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 619, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236812 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 736, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236946 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 760, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.339465 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 821, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254704 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 934, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236925 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 937, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254870 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 978, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236836 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1000, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236932 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1057, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254800 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1112, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236877 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1340, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236898 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1463, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254741 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1585, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236898 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1761, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.339907 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1854, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.237006 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1875, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236885 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1909, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236976 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 1973, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236918 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2002, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236883 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2091, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.321877 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2220, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236805 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2283, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236985 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2285, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254825 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2313, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254746 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2345, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236879 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2396, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236879 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2426, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236872 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2737, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236877 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2784, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254666 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 2994, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236984 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3003, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254716 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3047, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236918 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3202, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236853 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3252, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254756 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3439, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.339470 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3440, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254778 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3566, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236936 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3667, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236882 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3784, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236869 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3815, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254756 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3832, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254827 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3951, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236943 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 3984, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236896 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4017, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254974 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4139, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254669 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4186, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254730 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4192, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236917 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4267, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.237002 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4326, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236888 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4442, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236879 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4513, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254866 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4669, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254643 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4792, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254732 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4839, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236859 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 4850, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236921 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5068, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236902 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5101, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254694 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5117, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236917 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5191, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236781 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5287, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.321989 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5407, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236836 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5519, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.237019 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5579, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254708 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5687, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236867 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5744, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254889 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 5960, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236953 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6061, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254790 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6145, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236865 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6176, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254755 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6217, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254804 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6275, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236919 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6294, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236908 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6327, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254849 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6380, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236902 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6600, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236929 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6657, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236878 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6797, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254710 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6824, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236884 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6825, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.339715 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6843, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236860 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6855, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.321960 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6951, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236943 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 6982, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254868 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7039, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236891 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7075, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.255075 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7419, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.339693 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7425, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254850 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7443, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254832 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7492, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236982 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7595, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236958 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 7624, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236874 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8007, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236875 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8066, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254752 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8134, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254805 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8144, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236892 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8193, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236872 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8221, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236871 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8249, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.509529 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8342, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.321949 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8431, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236852 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8460, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254642 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8516, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236880 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8522, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254898 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8842, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236900 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 8952, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254745 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9381, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236895 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9384, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236889 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9414, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236834 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9439, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236877 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9654, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236956 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9678, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.236886 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9739, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.254661 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9833, Slowest CPU: 0 Fastest CPU: 3 ERROR: jitter = 0.255070 Jitter must be < 0.2 to pass ERROR: Failed Iteration = 9938, Slowest CPU: 0 Fastest CPU: 3 FAILED: 122 iterations failed