linux内核宏之——-PERF_ALIGN

#define PERF_ALIGN(x, a)    __PERF_ALIGN_MASK(x, (typeof(x))(a)-1)
#define __PERF_ALIGN_MASK(x, mask)    (((x)+(mask))&~(mask))

返回以a字节对齐需要的字节数，结果类似于roundup，例如：

PERF_ALIGN(9, 4) = 12;

PERF_ALIGN(11, 4) = 12;

PERF_ALIGN(6, 2) = 6;

#define roundup(x, y)                             
(                                                
    {                                           
        const typeof(y) __y = y;                   
        (((x) + (__y - 1)) / __y) * __y;        
    }                                           
)