Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 13 Nov 2022 13:26:20 +0530 | Subject | Re: [PATCH v7 0/9] Add latency priority for CFS class | From | shrikanth suresh hegde <> |
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> This patchset restarts the work about adding a latency priority to describe > the latency tolerance of cfs tasks. > > Hi Vincent.
Tested the patches on the power10 machine. It is 80 core system with SMT=8. i.e total of 640 cpus. on the large workload which mainly interacts with the database there is minor improvement of 3-5%.
the method followed is creating a cgroup, assigning a latency nice value of -20, -10, 0 and adding the tasks to procs of the cgroup. outside of cgroup, stress-ng load is running and it is not set any latency value. stress-ng --cpu=768 -l 50
with microbenchmarks, hackbench the values are more or less the same. for large process pool of 60, there is 10% improvement. schbench tail latencies show significant improvement with low and medium load upto 256 groups. only 512 groups shows a slight decline.
Hackbench (Iterations or N=50) Process 6.1_Base 6.1_Latency_Nice 10 0.13 0.14 20 0.18 0.18 30 0.24 0.25 40 0.34 0.33 50 0.40 0.41 60 0.53 0.49
schbench (Iterations or N=5)
Groups: 1 6.1_Base 6.1_Latency_Nice 50.0th: 10.8 9.8 75.0th: 12.4 11.4 90.0th: 14.2 13.2 95.0th: 15.6 14.6 99.0th: 27.8 19.0 99.5th: 38.0 21.6 99.9th: 66.2 25.4
Groups: 2 6.1_Base 6.1_Latency_Nice 50.0th: 11.2 10.8 75.0th: 13.2 12.4 90.0th: 15.0 15.0 95.0th: 16.6 16.6 99.0th: 22.4 22.8 99.5th: 23.8 27.8 99.9th: 30.2 45.6
Groups: 4 6.1_Base 6.1_Latency_Nice 50.0th: 13.8 11.2 75.0th: 16.0 13.2 90.0th: 18.6 15.2 95.0th: 20.4 16.6 99.0th: 28.8 21.6 99.5th: 48.8 25.2 99.9th: 900.2 47.0
Groups: 8 6.1_Base 6.1_Latency_Nice 50.0th: 17.8 14.4 75.0th: 21.8 17.2 90.0th: 25.4 20.4 95.0th: 28.0 22.4 99.0th: 52.8 28.4 99.5th: 156.4 32.6 99.9th: 1990.2 52.0
Groups: 16 6.1_Base 6.1_Latency_Nice 50.0th: 26.0 21.0 75.0th: 33.0 27.8 90.0th: 39.6 34.4 95.0th: 43.4 38.6 99.0th: 66.8 48.8 99.5th: 170.6 60.6 99.9th: 3308.8 201.6
Groups: 32 6.1_Base 6.1_Latency_Nice 50.0th: 40.8 38.6 75.0th: 55.4 52.8 90.0th: 67.0 64.2 95.0th: 74.2 71.6 99.0th: 106.0 90.0 99.5th: 323.8 133.0 99.9th: 4789.6 459.2
Groups: 64 6.1_Base 6.1_Latency_Nice 50.0th: 72.6 68.2 75.0th: 103.4 97.8 90.0th: 127.6 120.0 95.0th: 141.2 132.0 99.0th: 343.4 158.4 99.5th: 1609.0 180.8 99.9th: 6571.2 686.6
Groups: 128 6.1_Base 6.1_Latency_Nice 50.0th: 147.2 147.2 75.0th: 216.4 217.2 90.0th: 268.4 268.2 95.0th: 300.6 294.8 99.0th: 3500.0 638.6 99.5th: 5995.2 2522.8 99.9th: 10390.4 9451.2
Groups: 256 6.1_Base 6.1_Latency_Nice 50.0th: 340.8 333.2 75.0th: 551.8 530.2 90.0th: 3528.4 1919.2 95.0th: 7312.8 5558.4 99.0th: 14630.4 12912.0 99.5th: 17955.2 14950.4 99.9th: 23059.2 20230.4
Groups: 512 6.1_Base 6.1_Latency_Nice 50.0th: 1021.8 990.6 75.0th: 9545.6 10044.8 90.0th: 20972.8 21638.4 95.0th: 29971.2 30291.2 99.0th: 42355.2 46707.2 99.5th: 48550.4 52057.6 99.9th: 58867.2 60147.2
Tested-by: shrikanth Hegde <sshegde@linux.vnet.ibm.com>
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