8d791e5af1
bus_get_cpus() returns a specified set of CPUs for a device. It accepts an enum for the second parameter that indicates the type of cpuset to request. Currently two valus are supported: - LOCAL_CPUS (on x86 this returns all the CPUs in the package closest to the device when DEVICE_NUMA is enabled) - INTR_CPUS (like LOCAL_CPUS but only returns 1 SMT thread for each core) For systems that do not support NUMA (or if it is not enabled in the kernel config), LOCAL_CPUS fails with EINVAL. INTR_CPUS is mapped to 'all_cpus' by default. The idea is that INTR_CPUS should always return a valid set. Device drivers which want to use per-CPU interrupts should start using INTR_CPUS instead of simply assigning interrupts to all available CPUs. In the future we may wish to add tunables to control the policy of INTR_CPUS (e.g. should it be local-only or global, should it ignore SMT threads or not). The x86 nexus driver exposes the internal set of interrupt CPUs from the the x86 interrupt code via INTR_CPUS. The ACPI bus driver and PCI bridge drivers use _PXM to return a suitable LOCAL_CPUS set when _PXM exists and DEVICE_NUMA is enabled. They also and the global INTR_CPUS set from the nexus driver with the per-domain set from _PXM to generate a local INTR_CPUS set for child devices. Compared to the r298933, this version uses 'struct _cpuset' in <sys/bus.h> instead of 'cpuset_t' to avoid requiring <sys/param.h> (<sys/_cpuset.h> still requires <sys/param.h> for MAXCPU even though <sys/_bitset.h> does not after recent changes). |
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