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c39649c331
When initiating I/O on a multiqueue and multi-IRQ device, we may want to select a queue for which the response will be handled on the same or a nearby CPU. This requires a reverse-map of IRQ affinity. Add library functions to support a generic reverse-mapping from CPUs to objects with affinity and the specific case where the objects are IRQs. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
/*
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* cpu_rmap.c: CPU affinity reverse-map support
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* Copyright 2011 Solarflare Communications Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation, incorporated herein by reference.
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*/
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#include <linux/cpumask.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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/**
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* struct cpu_rmap - CPU affinity reverse-map
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* @size: Number of objects to be reverse-mapped
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* @used: Number of objects added
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* @obj: Pointer to array of object pointers
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* @near: For each CPU, the index and distance to the nearest object,
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* based on affinity masks
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*/
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struct cpu_rmap {
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u16 size, used;
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void **obj;
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struct {
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u16 index;
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u16 dist;
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} near[0];
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};
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#define CPU_RMAP_DIST_INF 0xffff
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extern struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags);
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/**
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* free_cpu_rmap - free CPU affinity reverse-map
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* @rmap: Reverse-map allocated with alloc_cpu_rmap(), or %NULL
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*/
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static inline void free_cpu_rmap(struct cpu_rmap *rmap)
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{
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kfree(rmap);
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}
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extern int cpu_rmap_add(struct cpu_rmap *rmap, void *obj);
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extern int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,
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const struct cpumask *affinity);
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static inline u16 cpu_rmap_lookup_index(struct cpu_rmap *rmap, unsigned int cpu)
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{
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return rmap->near[cpu].index;
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}
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static inline void *cpu_rmap_lookup_obj(struct cpu_rmap *rmap, unsigned int cpu)
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{
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return rmap->obj[rmap->near[cpu].index];
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}
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#ifdef CONFIG_GENERIC_HARDIRQS
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/**
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* alloc_irq_cpu_rmap - allocate CPU affinity reverse-map for IRQs
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* @size: Number of objects to be mapped
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*
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* Must be called in process context.
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*/
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static inline struct cpu_rmap *alloc_irq_cpu_rmap(unsigned int size)
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{
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return alloc_cpu_rmap(size, GFP_KERNEL);
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}
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extern void free_irq_cpu_rmap(struct cpu_rmap *rmap);
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extern int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq);
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#endif
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