forked from mirrors/linux
f867bac654
I found that blkp field was not used in kernel tree. As most of the times NR_CPUS is a power of two and kmalloc() memory blocks too, this extra field basically doubles the memory space allocated in __alloc_percpu() to store the 'struct percpu_data' (for example, if NR_CPUS=8 on i386, kmalloc(4*8+4) returns a 64 bytes block instead of a 32 bytes block after this patch) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
#ifndef __LINUX_PERCPU_H
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#define __LINUX_PERCPU_H
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#include <linux/spinlock.h> /* For preempt_disable() */
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#include <linux/slab.h> /* For kmalloc() */
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#include <linux/smp.h>
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#include <linux/string.h> /* For memset() */
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#include <asm/percpu.h>
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/* Enough to cover all DEFINE_PER_CPUs in kernel, including modules. */
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#ifndef PERCPU_ENOUGH_ROOM
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#define PERCPU_ENOUGH_ROOM 32768
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#endif
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/* Must be an lvalue. */
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#define get_cpu_var(var) (*({ preempt_disable(); &__get_cpu_var(var); }))
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#define put_cpu_var(var) preempt_enable()
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#ifdef CONFIG_SMP
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struct percpu_data {
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void *ptrs[NR_CPUS];
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};
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/*
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* Use this to get to a cpu's version of the per-cpu object allocated using
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* alloc_percpu. Non-atomic access to the current CPU's version should
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* probably be combined with get_cpu()/put_cpu().
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*/
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#define per_cpu_ptr(ptr, cpu) \
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({ \
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struct percpu_data *__p = (struct percpu_data *)~(unsigned long)(ptr); \
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(__typeof__(ptr))__p->ptrs[(cpu)]; \
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})
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extern void *__alloc_percpu(size_t size);
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extern void free_percpu(const void *);
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#else /* CONFIG_SMP */
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#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
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static inline void *__alloc_percpu(size_t size)
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{
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void *ret = kmalloc(size, GFP_KERNEL);
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if (ret)
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memset(ret, 0, size);
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return ret;
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}
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static inline void free_percpu(const void *ptr)
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{
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kfree(ptr);
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}
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#endif /* CONFIG_SMP */
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/* Simple wrapper for the common case: zeros memory. */
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#define alloc_percpu(type) ((type *)(__alloc_percpu(sizeof(type))))
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#endif /* __LINUX_PERCPU_H */
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