Shulou(Shulou.com)06/02 Report--

This article is about how to use the kmalloc kernel memory allocation function in Linux. The editor thinks it is very practical, so I share it with you. I hope you can get something after reading this article.

Define static _ _ always_inline void * kmalloc (size_t size, gfp_t flags) {if (_ _ builtin_constant_p (size)) {if (size > KMALLOC_MAX_CACHE_SIZE) return kmalloc_large (size, flags); # ifndef CONFIG_SLOB if (! (flags & GFP_DMA)) {int index = kmalloc_index (size) If (! index) return ZERO_SIZE_PTR; return kmem_cache_alloc_trace (kmalloc_caches [index], flags, size);} # endif} return _ kmalloc (size, flags);}

Note:

1) the _ _ builtin_constant_p compiler inlines the function to determine whether the incoming parameter is constant. If it is a variable, call the _ _ kmalloc function directly.

2) KMALLOC_MAX_CACHE_SIZE means that the maximum value of slab cache created by the system is 8K, which is defined as follows:

# # include/linux/slab.h/* Maximum size for which we actually use a slab cache * / # define KMALLOC_MAX_CACHE_SIZE (1UL

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