| # Copyright (c) 2024 Intel Corp. |
| # SPDX-License-Identifier: Apache-2.0 |
| # |
| menu "SMP Options" |
| |
| config SMP |
| bool "Symmetric multiprocessing support" |
| depends on USE_SWITCH |
| depends on !ATOMIC_OPERATIONS_C |
| help |
| When true, kernel will be built with SMP support, allowing |
| more than one CPU to schedule Zephyr tasks at a time. |
| |
| config USE_SWITCH |
| bool "Use new-style _arch_switch instead of arch_swap" |
| depends on USE_SWITCH_SUPPORTED |
| help |
| The _arch_switch() API is a lower level context switching |
| primitive than the original arch_swap mechanism. It is required |
| for an SMP-aware scheduler, or if the architecture does not |
| provide arch_swap. In uniprocess situations where the |
| architecture provides both, _arch_switch incurs more somewhat |
| overhead and may be slower. |
| |
| config USE_SWITCH_SUPPORTED |
| bool |
| help |
| Indicates whether _arch_switch() API is supported by the |
| currently enabled platform. This option should be selected by |
| platforms that implement it. |
| |
| config SMP_BOOT_DELAY |
| bool "Delay booting secondary cores" |
| depends on SMP |
| help |
| By default Zephyr will boot all available CPUs during start up. |
| Select this option to skip this and allow custom code |
| (architecture/SoC/board/application) to boot secondary CPUs at |
| a later time. |
| |
| config MP_NUM_CPUS |
| int "Number of CPUs/cores [DEPRECATED]" |
| default MP_MAX_NUM_CPUS |
| range 1 12 |
| help |
| This is deprecated, please use MP_MAX_NUM_CPUS instead. |
| |
| config MP_MAX_NUM_CPUS |
| int "Maximum number of CPUs/cores" |
| default 1 |
| range 1 12 |
| help |
| Maximum number of multiprocessing-capable cores available to the |
| multicpu API and SMP features. |
| |
| config SCHED_IPI_SUPPORTED |
| bool |
| help |
| True if the architecture supports a call to |
| arch_sched_ipi() to broadcast an interrupt that will call |
| z_sched_ipi() on other CPUs in the system. Required for |
| k_thread_abort() to operate with reasonable latency |
| (otherwise we might have to wait for the other thread to |
| take an interrupt, which can be arbitrarily far in the |
| future). |
| |
| config TRACE_SCHED_IPI |
| bool "Test IPI" |
| help |
| When true, it will add a hook into z_sched_ipi(), in order |
| to check if schedule IPI has called or not, for testing |
| purpose. |
| depends on SCHED_IPI_SUPPORTED |
| depends on MP_MAX_NUM_CPUS>1 |
| |
| config KERNEL_COHERENCE |
| bool "Place all shared data into coherent memory" |
| depends on ARCH_HAS_COHERENCE |
| default y if SMP && MP_MAX_NUM_CPUS > 1 |
| select THREAD_STACK_INFO |
| help |
| When available and selected, the kernel will build in a mode |
| where all shared data is placed in multiprocessor-coherent |
| (generally "uncached") memory. Thread stacks will remain |
| cached, as will application memory declared with |
| __incoherent. This is intended for Zephyr SMP kernels |
| running on cache-incoherent architectures only. Note that |
| when this is selected, there is an implicit API change that |
| assumes cache coherence to any memory passed to the kernel. |
| Code that creates kernel data structures in uncached regions |
| may fail strangely. Some assertions exist to catch these |
| mistakes, but not all circumstances can be tested. |
| |
| config TICKET_SPINLOCKS |
| bool "Ticket spinlocks for lock acquisition fairness [EXPERIMENTAL]" |
| select EXPERIMENTAL |
| help |
| Basic spinlock implementation is based on single |
| atomic variable and doesn't guarantee locking fairness |
| across multiple CPUs. It's even possible that single CPU |
| will win the contention every time which will result |
| in a live-lock. |
| Ticket spinlocks provide a FIFO order of lock acquisition |
| which resolves such unfairness issue at the cost of slightly |
| increased memory footprint. |
| |
| endmenu |
