kernel: smp: Optimize delivery of IPIs #69770
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The following west manifest projects have been modified in this Pull Request:
Note: This message is automatically posted and updated by the Manifest GitHub Action. |
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Rebased to resolve a merge conflict. |
npitre
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@peter-mitsis there is a failure because of another change in the SOF tree, I am working on resolving this now, but the conflict here not sure what is it about. |
nashif
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Jun 4, 2024
submanifests/optional.yaml
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| groups: | |||
| - optional | |||
| - name: sof | |||
| revision: c11a3185afbc8e1b2a79916de3dfefaf326d9ad1 | |||
| revision: ac1b774abfe2e8a9f6547f5bc305e499c51f9671 | |||
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point to this 1e4702f3080c68e6046b7b16eb030a3eba0ce231 instead.
ok, that was the esf change... |
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Updated submanifest as per @nashif's request -- nothing else changed. |
nashif
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Jun 4, 2024
evgeniy-paltsev
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npitre
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Jun 5, 2024
1. The flagging of IPIs is moved out of k_thread_priority_set() into z_thread_prio_set(). This allows for an IPI to be done for a thread that had its priority bumped due to the handling of priority inheritance from a mutex. 2. k_thread_priority_set()'s check for sched_locked only applies to non-SMP builds that are using the old arch_swap() framework to switch between threads. Incidentally, nearly all calls to flag_ipi() are now performed with sched_spinlock being locked. The only exception is in slice_timeout(). Signed-off-by: Peter Mitsis <[email protected]>
The CONFIG_IPI_OPTIMIZE configuration option allows for the flagging and subsequent signaling of IPIs to be optimized. It does this by making each bit in the kernel's pending_ipi field a flag that indicates whether the corresponding CPU might need an IPI to trigger the scheduling of a new thread on that CPU. When a new thread is made ready, we compare that thread against each of the threads currently executing on the other CPUs. If there is a chance that that thread should preempt the thread on the other CPU then we flag that an IPI is needed for that CPU. That is, a clear bit indicates that the CPU absolutely will not need to reschedule, while a set bit indicates that the target CPU must make that determination for itself. Signed-off-by: Peter Mitsis <[email protected]>
Platforms that support IPIs allow them to be broadcast via the new arch_sched_broadcast_ipi() routine (replacing arch_sched_ipi()). Those that also allow IPIs to be directed to specific CPUs may use arch_sched_directed_ipi() to do so. As the kernel has the capability to track which CPUs may need an IPI (see CONFIG_IPI_OPTIMIZE), this commit updates the signalling of tracked IPIs to use the directed version if supported; otherwise they continue to use the broadcast version. Platforms that allow directed IPIs may see a significant reduction in the number of IPI related ISRs when CONFIG_IPI_OPTIMIZE is enabled and the number of CPUs increases. These platforms can be identified by the Kconfig option CONFIG_ARCH_HAS_DIRECTED_IPIS. Signed-off-by: Peter Mitsis <[email protected]>
Updates the sof revision. This is needed for it to pick up a change to the arch_sched_ipi() which has been renamed to arch_sched_broadcast_ipi(). Signed-off-by: Peter Mitsis <[email protected]>
Adds several tests to verify that IPIs can be appropriately targeted to specific CPUs. Signed-off-by: Peter Mitsis <[email protected]>
nashif
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nashif
approved these changes
Jun 5, 2024
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This set of commits is a step towards optimising the delivery of inter-processor interrupts (IPIs). It does this by attempting to deliver IPIs only to relevant CPUs.
The bulk of these changes revolve around three ideas.