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
/*
|
|
* cpu_rmap.c: CPU affinity reverse-map support
|
|
* Copyright 2011 Solarflare Communications Inc.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 as published
|
|
* by the Free Software Foundation, incorporated herein by reference.
|
|
*/
|
|
|
|
#include <linux/cpumask.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/slab.h>
|
|
|
|
/**
|
|
* struct cpu_rmap - CPU affinity reverse-map
|
|
* @size: Number of objects to be reverse-mapped
|
|
* @used: Number of objects added
|
|
* @obj: Pointer to array of object pointers
|
|
* @near: For each CPU, the index and distance to the nearest object,
|
|
* based on affinity masks
|
|
*/
|
|
struct cpu_rmap {
|
|
u16 size, used;
|
|
void **obj;
|
|
struct {
|
|
u16 index;
|
|
u16 dist;
|
|
} near[0];
|
|
};
|
|
#define CPU_RMAP_DIST_INF 0xffff
|
|
|
|
extern struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags);
|
|
|
|
/**
|
|
* free_cpu_rmap - free CPU affinity reverse-map
|
|
* @rmap: Reverse-map allocated with alloc_cpu_rmap(), or %NULL
|
|
*/
|
|
static inline void free_cpu_rmap(struct cpu_rmap *rmap)
|
|
{
|
|
kfree(rmap);
|
|
}
|
|
|
|
extern int cpu_rmap_add(struct cpu_rmap *rmap, void *obj);
|
|
extern int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,
|
|
const struct cpumask *affinity);
|
|
|
|
static inline u16 cpu_rmap_lookup_index(struct cpu_rmap *rmap, unsigned int cpu)
|
|
{
|
|
return rmap->near[cpu].index;
|
|
}
|
|
|
|
static inline void *cpu_rmap_lookup_obj(struct cpu_rmap *rmap, unsigned int cpu)
|
|
{
|
|
return rmap->obj[rmap->near[cpu].index];
|
|
}
|
|
|
|
#ifdef CONFIG_GENERIC_HARDIRQS
|
|
|
|
/**
|
|
* alloc_irq_cpu_rmap - allocate CPU affinity reverse-map for IRQs
|
|
* @size: Number of objects to be mapped
|
|
*
|
|
* Must be called in process context.
|
|
*/
|
|
static inline struct cpu_rmap *alloc_irq_cpu_rmap(unsigned int size)
|
|
{
|
|
return alloc_cpu_rmap(size, GFP_KERNEL);
|
|
}
|
|
extern void free_irq_cpu_rmap(struct cpu_rmap *rmap);
|
|
|
|
extern int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq);
|
|
|
|
#endif
|