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| author | Peter Zijlstra <peterz@infradead.org> | 2023-05-31 13:58:44 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2023-07-19 09:43:58 +0200 |
| commit | 147f3efaa24182a21706bca15eab2f3f4630b5fe (patch) | |
| tree | 555ff76e8d3aabc2e62f43856e50ebff7e3bfbd9 /kernel/sched/features.h | |
| parent | 99d4d26551b56f4e523dd04e4970b94aa796a64e (diff) | |
| download | linux-147f3efaa24182a21706bca15eab2f3f4630b5fe.tar.gz linux-147f3efaa24182a21706bca15eab2f3f4630b5fe.tar.bz2 linux-147f3efaa24182a21706bca15eab2f3f4630b5fe.zip | |
sched/fair: Implement an EEVDF-like scheduling policy
Where CFS is currently a WFQ based scheduler with only a single knob,
the weight. The addition of a second, latency oriented parameter,
makes something like WF2Q or EEVDF based a much better fit.
Specifically, EEVDF does EDF like scheduling in the left half of the
tree -- those entities that are owed service. Except because this is a
virtual time scheduler, the deadlines are in virtual time as well,
which is what allows over-subscription.
EEVDF has two parameters:
- weight, or time-slope: which is mapped to nice just as before
- request size, or slice length: which is used to compute
the virtual deadline as: vd_i = ve_i + r_i/w_i
Basically, by setting a smaller slice, the deadline will be earlier
and the task will be more eligible and ran earlier.
Tick driven preemption is driven by request/slice completion; while
wakeup preemption is driven by the deadline.
Because the tree is now effectively an interval tree, and the
selection is no longer 'leftmost', over-scheduling is less of a
problem.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.931005524@infradead.org
Diffstat (limited to 'kernel/sched/features.h')
| -rw-r--r-- | kernel/sched/features.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 7958a10fe23b..60cce1e6f37b 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -13,6 +13,7 @@ SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true) * sleep+wake cycles. EEVDF placement strategy #1, #2 if disabled. */ SCHED_FEAT(PLACE_LAG, true) +SCHED_FEAT(PLACE_DEADLINE_INITIAL, true) /* * Prefer to schedule the task we woke last (assuming it failed @@ -103,3 +104,5 @@ SCHED_FEAT(LATENCY_WARN, false) SCHED_FEAT(ALT_PERIOD, true) SCHED_FEAT(BASE_SLICE, true) + +SCHED_FEAT(EEVDF, true) |