nginx slab 申请大小与地址的对应关系

参考文章：https://www.cnblogs.com/jimodetiantang/p/9193858.html
// 连续申请共享内存时，128字节是系统之前申请的。
ctx->sh:0x7fff6f4c8000 // 系统申请的80字节，实际占用128字节
8    p1:0x7fff6f4c9040, p2:0x7fff6f4c9048,p3:0x7fff6f4c9050,p4:0x7fff6f4c9058,p5:0x7fff6f4c9060
32   p1:0x7fff6f4ca020, p2:0x7fff6f4ca040,p3:0x7fff6f4ca060,p4:0x7fff6f4ca080,p5:0x7fff6f4ca0a0
64   p1:0x7fff6f4cb000, p2:0x7fff6f4cb040,p3:0x7fff6f4cb080,p4:0x7fff6f4cb0c0,p5:0x7fff6f4cb100
128  p1:0x7fff6f4c8080, p2:0x7fff6f4c8100,p3:0x7fff6f4c8180,p4:0x7fff6f4c8200,p5:0x7fff6f4c8280
256  p1:0x7fff6f4cc000, p2:0x7fff6f4cc100,p3:0x7fff6f4cc200,p4:0x7fff6f4cc300,p5:0x7fff6f4cc400
512  p1:0x7fff6f4cd000, p2:0x7fff6f4cd200,p3:0x7fff6f4cd400,p4:0x7fff6f4cd600,p5:0x7fff6f4cd800
1024 p1:0x7fff6f4ce000, p2:0x7fff6f4ce400,p3:0x7fff6f4ce800,p4:0x7fff6f4cec00,p5:0x7fff6f4cf000

// 申请8字节页之后删除8字节页，然后连续申请，最后申请8字节
ctx->sh:0x7fff6f4c8000 // 系统申请的80字节，实际占用128字节
8      p1:0x7fff6f4c9040, p2:0x7fff6f4c9048,p3:0x7fff6f4c9050,p4:0x7fff6f4c9058,p5:0x7fff6f4c9060
32    p1:0x7fff6f4c9020, p2:0x7fff6f4c9040,p3:0x7fff6f4c9060,p4:0x7fff6f4c9080,p5:0x7fff6f4c90a0
64    p1:0x7fff6f4ca000, p2:0x7fff6f4ca040,p3:0x7fff6f4ca080,p4:0x7fff6f4ca0c0,p5:0x7fff6f4ca100
128   p1:0x7fff6f4c8080, p2:0x7fff6f4c8100,p3:0x7fff6f4c8180,p4:0x7fff6f4c8200,p5:0x7fff6f4c8280
256   p1:0x7fff6f4cb000, p2:0x7fff6f4cb100,p3:0x7fff6f4cb200,p4:0x7fff6f4cb300,p5:0x7fff6f4cb400
512   p1:0x7fff6f4cc000, p2:0x7fff6f4cc200,p3:0x7fff6f4cc400,p4:0x7fff6f4cc600,p5:0x7fff6f4cc800
1024  p1:0x7fff6f4cd000, p2:0x7fff6f4cd400,p3:0x7fff6f4cd800,p4:0x7fff6f4cdc00,p5:0x7fff6f4ce000
8     p1:0x7fff6f4cf040

// 申请8字节页后，free第一个8字节(p1)内容，最后申请的8字节覆盖在删除的8字节
ctx->sh:0x7fff6f4c8000 // 系统申请的80字节，实际占用128字节
8        p1:0x7fff6f4c9040, p2:0x7fff6f4c9048,p3:0x7fff6f4c9050,p4:0x7fff6f4c9058,p5:0x7fff6f4c9060
32         p1:0x7fff6f4ca020, p2:0x7fff6f4ca040,p3:0x7fff6f4ca060,p4:0x7fff6f4ca080,p5:0x7fff6f4ca0a0
64         p1:0x7fff6f4cb000, p2:0x7fff6f4cb040,p3:0x7fff6f4cb080,p4:0x7fff6f4cb0c0,p5:0x7fff6f4cb100
128     p1:0x7fff6f4c8080, p2:0x7fff6f4c8100,p3:0x7fff6f4c8180,p4:0x7fff6f4c8200,p5:0x7fff6f4c8280
256     p1:0x7fff6f4cc000, p2:0x7fff6f4cc100,p3:0x7fff6f4cc200,p4:0x7fff6f4cc300,p5:0x7fff6f4cc400
512     p1:0x7fff6f4cd000, p2:0x7fff6f4cd200,p3:0x7fff6f4cd400,p4:0x7fff6f4cd600,p5:0x7fff6f4cd800
1024     p1:0x7fff6f4ce000, p2:0x7fff6f4ce400,p3:0x7fff6f4ce800,p4:0x7fff6f4cec00,p5:0x7fff6f4cf000
8        p1:0x7fff6f4c9040