scx_lavd: improve virtual deadline calculation #197
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added 4 commits
March 21, 2024 10:32
Take slice_boost_prio -- how many times a full time slice was consumed -- into consideration in calculating run_time_ns (runtime per schedule). This improve the accuracy especially when a task is overscheduled and its time slice is reduced for enforcing fairness. Signed-off-by: Changwoo Min <changwoo@igalia.com>
As the calculated runtime increases by considering the number of full-time slice consumption, increase the upper bound (LAVD_LC_RUNTIME_MAX) of runtime to be considered in latency calculation. Also, add LAVD_SLICE_BOOST_MAX_PRIO to avoid slice_boost_prio dropping to zero suddenly. Signed-off-by: Changwoo Min <changwoo@igalia.com>
Replace a latency weight arrary to more skewed one, which is the inverse of sched_prio_to_slice_weight. It turns out more skewed one works better under highly CPU-overloaded cases since it gives a longer deadline to non-latency-critical tasks. Signed-off-by: Changwoo Min <changwoo@igalia.com>
The old approach is mapping [0, maximum latency criticliy] to [-boost range, boost range). This approach is easily affected by one outlier maximum value and suffers from the integer truncation error. The new approach divides the range into two -- [minimum latency criticality, average latency criticality) and [average latency criticality, maximum latency criticality] -- and maps them into [boost range/2, 0) and [0, -boost range/2), respectively, Signed-off-by: Changwoo Min <changwoo@igalia.com>
htejun
approved these changes
Mar 26, 2024
added 2 commits
March 28, 2024 06:45
The current description is a bit confusing, so update the comments for clarity. Signed-off-by: Changwoo Min <changwoo@igalia.com>
The run_time_boosted_ns calculation requires updated slice_boost_prio, so updating slice_boost_prio should be done before updating run_time_boosted_ns. Signed-off-by: Changwoo Min <changwoo@igalia.com>
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This PR improves the virtual deadline calculation. It consists of four commits including
These changes help especially for over-loaded cases.