{"id":1547,"date":"2012-03-19T14:29:03","date_gmt":"2012-03-19T05:29:03","guid":{"rendered":"http:\/\/peta.okechan.net\/blog\/?p=1547"},"modified":"2014-02-23T23:06:19","modified_gmt":"2014-02-23T14:06:19","slug":"xv6-45-chapter-4-scheduling-code-context-switching","status":"publish","type":"post","link":"https:\/\/peta.okechan.net\/blog\/archives\/1547","title":{"rendered":"[xv6 #45] Chapter 4 – Scheduling – Code: Context switching"},"content":{"rendered":"

\u30c6\u30ad\u30b9\u30c8\u306e51\u301c53\u30da\u30fc\u30b8<\/p>\n

\u672c\u6587<\/h3>\n

\u56f34-1\u3067\u793a\u3055\u308c\u308b\u3088\u3046\u306b\u3001\u30d7\u30ed\u30bb\u30b9\u3092\u5207\u308a\u66ff\u3048\u308b\u305f\u3081\u306b\u3001xv6\u306f\u30ed\u30fc\u30ec\u30d9\u30eb\u30672\u7a2e\u985e\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u30b9\u30a4\u30c3\u30c1\u3092\u884c\u3046\u3002
\n\u3072\u3068\u3064\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u73fe\u5728\u306eCPU\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u5207\u308a\u66ff\u3048\u3001\u3082\u3046\u3072\u3068\u3064\u306f\u3001\u305d\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u5207\u308a\u66ff\u3048\u3067\u3042\u308b\u3002
\nxv6\u306f\u3001\u30e6\u30fc\u30b6\u7a7a\u9593\u306e\u30d7\u30ed\u30bb\u30b9\u304b\u3089\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u3078\u76f4\u63a5\u5207\u308a\u66ff\u3048\u308b\u3053\u3068\u306f\u6c7a\u3057\u3066\u3057\u306a\u3044\u3002
\n\u3053\u306e\u3053\u3068\u306f\u3001\u30e6\u30fc\u30b6\u30ab\u30fc\u30cd\u30eb\u306e\u9077\u79fb\uff08\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3084\u5272\u308a\u8fbc\u307f\uff09\u306e\u3084\u308a\u65b9\u306b\u3088\u3063\u3066\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u3078\u306e\u5207\u308a\u66ff\u3048\u3001\u65b0\u3057\u3044\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u30b9\u30a4\u30c3\u30c1\u3001\u305d\u3057\u3066\u30c8\u30e9\u30c3\u30d7\u304b\u3089\u623b\u308b\u3068\u3044\u3046\u4e8b\u3092\u5f15\u304d\u8d77\u3053\u3059\u3002
\n\u3053\u306e\u7bc0\u3067\u306f\u3001\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3068\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b9\u30ec\u30c3\u30c9\u306e\u9593\u306e\u5207\u308a\u66ff\u3048\u306e\u4ed5\u7d44\u307f\u306b\u3064\u3044\u3066\u8aac\u660e\u3059\u308b\u3002<\/p>\n

\"\"<\/a>
\n\u56f34\u22121 \u3042\u308b\u30e6\u30fc\u30b6\u30d7\u30ed\u30bb\u30b9\u304b\u3089\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u3078\u306e\u5207\u308a\u66ff\u3048\u3002\u3053\u306e\u4f8b\u3067\u306f\u3001xv6\u306f\u4e00\u3064\u306eCPU\u3067\u5b9f\u884c\u3055\u308c\u3066\u3044\u308b\u3002\uff08\u3088\u3063\u3066\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30ec\u30c3\u30c9\u3082\u3072\u3068\u3064\u3067\u3042\u308b\uff09<\/p>\n

xv6\u306e\u30d7\u30ed\u30bb\u30b9\u306f\u3069\u308c\u3067\u3082\u3001\u7b2c1\u7ae0\u3067\u898b\u3066\u304d\u305f\u3088\u3046\u306b\u3001\u305d\u308c\u81ea\u8eab\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30bf\u30c3\u30af\u3068\u30ec\u30b8\u30b9\u30bf\u4e00\u5f0f\u3092\u6301\u3064\u3002
\n\u305d\u308c\u305e\u308c\u306eCPU\u306f\u3001\u3069\u3053\u304b\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3067\u306f\u306a\u304f\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u3092\u5b9f\u884c\u3057\u3066\u3044\u308b\u3068\u304d\u306b\u4f7f\u3046\u305f\u3081\u306e\u500b\u5225\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b9\u30ec\u30c3\u30c9\u3092\u6301\u3064\u3002
\n\u3042\u308b\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u4ed6\u306e\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u5207\u308a\u66ff\u3048\u306f\u3001\u5207\u308a\u66ff\u3048\u5143\u3082\u30b9\u30ec\u30c3\u30c9\u306eCPU\u30ec\u30b8\u30b9\u30bf\u306e\u4fdd\u5b58\u3068\u3001\u5207\u308a\u66ff\u3048\u5148\u306e\u30b9\u30ec\u30c3\u30c9\u306e\u4ee5\u524d\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30ec\u30b8\u30b9\u30bf\u306e\u5fa9\u5143\u3092\u4f34\u3046\u3002
\n%esp\u3068%eip\u304c\u4fdd\u5b58\u3084\u5fa9\u5143\u3055\u308c\u308b\u3068\u3044\u3046\u4e8b\u5b9f\u306f\u3001CPU\u304c\u30b9\u30bf\u30c3\u30af\u3092\u5207\u308a\u66ff\u3048\u3001\u3069\u306e\u30b3\u30fc\u30c9\u304c\u5b9f\u884c\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u5207\u308a\u66ff\u3048\u308b\u3068\u3044\u3046\u4e8b\u3092\u610f\u5473\u3059\u308b\u3002<\/p>\n

swtch\u306f\u30b9\u30ec\u30c3\u30c9\u306b\u3064\u3044\u3066\u306f\u76f4\u63a5\u7684\u306b\u306f\u77e5\u3089\u306a\u3044\u3002
\n\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3068\u547c\u3070\u308c\u308b\u30ec\u30b8\u30b9\u30bf\u4e00\u5f0f\u3092\u4fdd\u5b58\u3057\u5fa9\u5143\u3059\u308b\u3060\u3051\u3067\u3042\u308b\u3002
\n\u30d7\u30ed\u30bb\u30b9\u306bCPU\u3092\u624b\u653e\u3055\u305b\u308b\u3068\u304d\u304c\u6765\u305f\u3068\u304d\u3001\u305d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u306f\u3001\u81ea\u8eab\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u4fdd\u5b58\u3057\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306b\u623b\u308b\u305f\u3081\u306bswtch\u3092\u547c\u3076\u3060\u308d\u3046\u3002
\n\u305d\u308c\u305e\u308c\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306f\u3001struct context*\u3068\u3057\u3066\u8868\u73fe\u3055\u308c\u3001\u5dfb\u304d\u8fbc\u307e\u308c\u305f\u30ab\u30fc\u30cd\u30eb\u30b9\u30bf\u30c3\u30af\u4e0a\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30c7\u30fc\u30bf\u69cb\u9020\u3092\u6307\u3059\u30dd\u30a4\u30f3\u30bf\u3067\u3042\u308b\u3002
\nswtch\u306f2\u3064\u306e\u5f15\u6570\u3092\u53d7\u3051\u53d6\u308b\u3002
\nstruct context **old\u3068struct context *new\u3067\u3042\u308b\u3002
\nswtch\u306f\u3001\u73fe\u5728\u306eCPU\u30ec\u30b8\u30b9\u30bf\u306e\u5024\u3092\u30b9\u30bf\u30c3\u30af\u306b\u30d7\u30c3\u30b7\u30e5\u3057\u3001\u305d\u306e\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u3092*old\u306b\u4fdd\u5b58\u3059\u308b\u3002
\n\u305d\u3057\u3066swtch\u306f\u3001new\u304b\u3089%esp\u306b\u30b3\u30d4\u30fc\u3057\u3001\u4ee5\u524d\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30ec\u30b8\u30b9\u30bf\u3092\u53d6\u308a\u51fa\u3057\u3001\u305d\u3057\u3066\u623b\u308b\u3002<\/p>\n

proc.h\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308bcontext\u69cb\u9020\u4f53<\/p>\n

\/\/ Saved registers for kernel context switches.\r\n\/\/ Don't need to save all the segment registers (%cs, etc),\r\n\/\/ because they are constant across kernel contexts.\r\n\/\/ Don't need to save %eax, %ecx, %edx, because the\r\n\/\/ x86 convention is that the caller has saved them.\r\n\/\/ Contexts are stored at the bottom of the stack they\r\n\/\/ describe; the stack pointer is the address of the context.\r\n\/\/ The layout of the context matches the layout of the stack in swtch.S\r\n\/\/ at the "Switch stacks" comment. Switch doesn't save eip explicitly,\r\n\/\/ but it is on the stack and allocproc() manipulates it.\r\nstruct context {\r\n  uint edi;\r\n  uint esi;\r\n  uint ebx;\r\n  uint ebp;\r\n  uint eip;\r\n};<\/pre>\n
swtch.S<\/p>\n
# Context switch\r\n#\r\n#   void swtch(struct context **old, struct context *new);\r\n# \r\n# Save current register context in old\r\n# and then load register context from new.\r\n\r\n.globl swtch\r\nswtch:\r\n  movl 4(%esp), %eax\r\n  movl 8(%esp), %edx\r\n\r\n  # Save old callee-save registers\r\n  pushl %ebp\r\n  pushl %ebx\r\n  pushl %esi\r\n  pushl %edi\r\n\r\n  # Switch stacks\r\n  movl %esp, (%eax)\r\n  movl %edx, %esp\r\n\r\n  # Load new callee-save registers\r\n  popl %edi\r\n  popl %esi\r\n  popl %ebx\r\n  popl %ebp\r\n  ret<\/pre>\n
Instead of following the scheduler into swtch, let\u2019s instead follow our user process back in.\uff08\u3053\u3053\u8a33\u304c\u5206\u304b\u3089\u306a\u3044\uff09<\/del>
\n\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u304b\u3089swtch\u3078\u306e\u6d41\u308c\u3092\u8ffd\u3046\u4ee3\u308f\u308a\u306b\u3001\u30e6\u30fc\u30b6\u30fc\u30d7\u30ed\u30bb\u30b9\u304c\u623b\u3063\u3066\u304f\u308b\u6d41\u308c\u3092\u8ffd\u3063\u3066\u307f\u3088\u3046\u3002<\/ins>
\n\u305d\u308c\u305e\u308c\u306e\u5272\u308a\u8fbc\u307f\u306e\u6700\u5f8c\u306btrap\u95a2\u6570\u304cyield\u95a2\u6570\u3092\u547c\u3076\u53ef\u80fd\u6027\u306b\u3064\u3044\u3066\u3001\u6211\u3005\u306f\u7b2c2\u7ae0\u3067\u898b\u305f\u3002
\n\u540c\u69d8\u306byield\u95a2\u6570\u306f\u3001\u73fe\u5728\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092proc->context\u3078\u4fdd\u5b58\u3057\u3001\u4ee5\u524d\u306bcpu->scheduler\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3078\u5207\u308a\u66ff\u3048\u308b\u305f\u3081\u306eswtch\u3092\u547c\u3076sched\u95a2\u6570\u3001\u3092\u547c\u3076\u3002<\/p>\n
proc.c\u306esched\u95a2\u6570\u3068yield\u95a2\u6570<\/p>\n
\/\/ Enter scheduler.  Must hold only ptable.lock\r\n\/\/ and have changed proc->state.\r\nvoid\r\nsched(void)\r\n{\r\n  int intena;\r\n\r\n  if(!holding(&ptable.lock))\r\n    panic("sched ptable.lock");\r\n  if(cpu->ncli != 1)\r\n    panic("sched locks");\r\n  if(proc->state == RUNNING)\r\n    panic("sched running");\r\n  if(readeflags()&FL_IF)\r\n    panic("sched interruptible");\r\n  intena = cpu->intena;\r\n  swtch(&proc->context, cpu->scheduler);\r\n  cpu->intena = intena;\r\n}\r\n\r\n\/\/ Give up the CPU for one scheduling round.\r\nvoid\r\nyield(void)\r\n{\r\n  acquire(&ptable.lock);  \/\/DOC: yieldlock\r\n  proc->state = RUNNABLE;\r\n  sched();\r\n  release(&ptable.lock);\r\n}<\/pre>\n
swtch\u306f\u3001%eax\u30ec\u30b8\u30b9\u30bf\u3068%edx\u30ec\u30b8\u30b9\u30bf\u3078\u81ea\u8eab\u306e\u5f15\u6570\u3092\u8aad\u307f\u8fbc\u3080\u4e8b\u304b\u3089\u958b\u59cb\u3059\u308b\u3002
\n\u3053\u308c\u306f\u5fc5\u8981\u306a\u51e6\u7406\u3067\u3042\u308b\u3002
\n\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u3092\u5909\u66f4\u3059\u308b\u3068\u3001\u3082\u306f\u3084%esp\u7d4c\u7531\u3067\u5f15\u6570\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u3053\u3068\u304c\u51fa\u6765\u306a\u304f\u306a\u308b\u304b\u3089\u3067\u3042\u308b\u3002
\n\u305d\u3057\u3066swtch\u306f\u3001\u73fe\u5728\u306e\u30b9\u30bf\u30c3\u30af\u4e0a\u306bcontext\u69cb\u9020\u4f53\u3092\u4f5c\u308b\u305f\u3081\u3001\u30ec\u30b8\u30b9\u30bf\u306e\u72b6\u614b\u3092\u30d7\u30c3\u30b7\u30e5\u3059\u308b\u3002
\n\u547c\u3073\u51fa\u3055\u308c\u308b\u5074\u3067\u4fdd\u5b58\u3055\u308c\u308b\u30ec\u30b8\u30b9\u30bf\u3060\u3051\u4fdd\u5b58\u3055\u308c\u308b\u5fc5\u8981\u304c\u3042\u308b\u3002
\nx86\u306e\u6163\u7fd2\u3067\u306f\u3001\u305d\u308c\u3089\u306f%ebp, %ebx, %esi, %ebp, %esp\u3067\u3042\u308b\u3002
\nswtch\u306f\u3001\u6700\u521d\u306e4\u3064\u3092\u76f4\u63a5\u30d7\u30c3\u30b7\u30e5\u3059\u308b\u3002\uff08# Save old callee\u2212save registers\u306e\u3068\u3053\u308d\uff09
\n\u9593\u63a5\u7684\u306bstruct context*\u3068\u3057\u3066*old\u306b\u66f8\u304d\u8fbc\u3080\u305f\u3081\u306b\u6700\u5f8c\u306e\u3082\u306e\u3092\u4fdd\u5b58\u3059\u308b\u3002\uff08movl %esp, (%eax)\u306e\u3068\u3053\u308d\uff09
\n\u3082\u3046\u3072\u3068\u3064\u91cd\u8981\u306a\u30ec\u30b8\u30b9\u30bf\u304c\u3042\u308b\u3002
\n\u30d7\u30ed\u30b0\u30e9\u30e0\u30ab\u30a6\u30f3\u30bf%eip\u306f\u3001swtch\u3092\u547c\u3073\u51fa\u3057\u305fcall\u547d\u4ee4\u306b\u3088\u3063\u3066\u4fdd\u5b58\u3055\u308c\u3001%ebp\u306e\u3061\u3087\u3046\u3069\u3059\u3050\u4e0a\u4f4d\u306e\u30b9\u30bf\u30c3\u30af\u306b\u3042\u308b\u3002
\n\u53e4\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u304c\u4fdd\u5b58\u3055\u308c\u305f\u3089\u3001swtch\u306f\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5fa9\u5143\u3059\u308b\u6e96\u5099\u3092\u3059\u308b\u3002
\n\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306e\u30dd\u30a4\u30f3\u30bf\u3092\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u306b\u79fb\u52d5\u3059\u308b\u3002\uff08movl %edx, %esp\u306e\u3068\u3053\u308d\uff09
\n\u65b0\u3057\u3044\u30b9\u30bf\u30c3\u30af\u306f\u3001swtch\u304c\u3061\u3087\u3046\u3069\u3044\u307e\u51e6\u7406\u3057\u305f\u3070\u304b\u308a\u306e\u53e4\u3044\u30b9\u30bf\u30c3\u30af\u3068\u540c\u3058\u5f62\u5f0f\u3067\u3042\u308a\u3001\uff08\u524d\u56de\u306eswtch\u306e\u547c\u3073\u51fa\u3057\u3067\u306f\u305d\u306e\u65b0\u3057\u3044\u30b9\u30bf\u30c3\u30af\u306f\u53e4\u3044\u30b9\u30bf\u30c3\u30af\u3060\u3063\u305f\uff09swtch\u306f\u9006\u306e\u624b\u9806\u3067\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5fa9\u5143\u3059\u308b\u3002
\n%edi, %esi, %ebx, %ebp\u3092\u30dd\u30c3\u30d7\u3057\u3001\u305d\u3057\u3066\u623b\u308b\u3002\uff08# Load new callee\u2212save registers\u306e\u3068\u3053\u308d\uff09
\nswtch\u306f\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u3092\u5909\u66f4\u3059\u308b\u306e\u3067\u3001\u5fa9\u5143\u3055\u308c\u305f\u5024\u3068\u623b\u308a\u5148\u306e\u547d\u4ee4\u30a2\u30c9\u30ec\u30b9\u306f\u3001\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306e\u3082\u306e\u3068\u306a\u308b\u3002<\/p>\n
\u6211\u3005\u306e\u4f8b\u3067\u306f\u3001sched\u306fCPU\u3054\u3068\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3067\u3042\u308bcpu->scheduler\u3078\u5207\u308a\u66ff\u3048\u308b\u305f\u3081\u306bswtch\u3092\u547c\u3093\u3060\u3002
\n\u305d\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306f\u3001scheduler\u95a2\u6570\u306b\u3088\u308bswtch\u306e\u547c\u3073\u51fa\u3057\u306b\u3088\u3063\u3066\u3059\u3067\u306b\u4fdd\u5b58\u3055\u308c\u305f\u3082\u306e\u3067\u3042\u308b\u3002
\n\u6211\u3005\u304c\u8ffd\u8de1\u3057\u3066\u3044\u308bswtch\u304b\u3089\u623b\u3063\u305f\u3068\u304d\u3001sched\u3067\u306f\u306a\u304fscheduler\u3078\u623b\u308a\u3001\u305d\u3057\u3066\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u306f\u3001initproc\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30bf\u30c3\u30af\u3067\u306f\u306a\u304f\u3001\u73fe\u5728\u306eCPU\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30bf\u30c3\u30af\u3092\u6307\u3059\u72b6\u614b\u306b\u306a\u3063\u3066\u3044\u308b\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
\u6fc3\u3044\u7bc0\u3067\u3057\u305f\u3002
\n\u307e\u3068\u3081\u308b\u3068\u3001
\n\u30d7\u30ed\u30bb\u30b9\u3092\u5207\u308a\u66ff\u3048\u308b\u969b\u306f\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306b\u4e00\u65e6\u5207\u308a\u66ff\u3048\u3066\u304b\u3089\u3001\u76ee\u7684\u306e\u30d7\u30ed\u30bb\u30b9\u306b\u5207\u308a\u66ff\u3048\u308b\u3002
\n\u5207\u308a\u66ff\u3048\u51e6\u7406\u306e\u30b3\u30a2\u306fswtch\u3067\u3042\u308b\u3002
\nswtch\u3067\u306f\u3001\u5207\u308a\u66ff\u3048\u5143\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u4fdd\u5b58\u3057\u3066\u3001\u5207\u308a\u66ff\u3048\u5148\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5fa9\u5143\u3059\u308b\u3002
\n\u3063\u3066\u3068\u3053\u308d\u3067\u3059\u304b\u306d\u3002<\/p>\n
yield\u306e\u8aac\u660e\u306e\u3068\u3053\u308d\u3067\u306f\u8a33\u304c\u3088\u304f\u5206\u304b\u3089\u306a\u3044\u6587\u304c\u3042\u308a\u307e\u3059\u304c\u3001\u30bd\u30fc\u30b9\u3092\u898b\u308b\u3068trap\u95a2\u6570\u306e\u6700\u5f8c\u306b\u30bf\u30a4\u30de\u5272\u308a\u8fbc\u307f\u3060\u3063\u305f\u3089yield\u3092\u5b9f\u884c\u3059\u308b\u3068\u3044\u3046\u30b3\u30fc\u30c9\u304c\u3042\u308a\u3001\u305d\u3053\u304c\u6642\u5206\u5272\u306e\u30ad\u30e2\u3068\u306a\u308b\u90e8\u5206\u304b\u3068\u601d\u3044\u307e\u3059\u3002
\n\u305d\u3053\u3067\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b9\u30ec\u30c3\u30c9\u3078\u5207\u308a\u66ff\u308f\u308a\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306fRUNNABLE\u306a\u30d7\u30ed\u30bb\u30b9\u3092\u63a2\u3057\u3066\u305d\u308c\u306b\u5207\u308a\u66ff\u3048\u308b\u3001\u3068\u3044\u3046\u51e6\u7406\u304c\u884c\u308f\u308c\u308b\u306f\u305a\u3067\u3059\u3002<\/p>\n
\u6700\u5f8c\u306einitproc\u306a\u3093\u3061\u3083\u3089\u306e\u3068\u3053\u308d\u306f\u3001\u7b2c1\u7ae0\u306eCode: Running a process\u3067\u8aac\u660e\u304c\u3042\u3063\u305f\u90e8\u5206\u3067\u3059\u3002
\nswtch\u306f\u8d77\u52d5\u4e2d\u306e\u7279\u5225\u306a\u51e6\u7406\u3067\u3082\u4f7f\u308f\u308c\u308b\u306e\u3067\u3059\u304c\u3001\u5358\u306b\u4eca\u56de\u306f\uff08\u3068\u3044\u3046\u304b\u3053\u3061\u3089\u304c\u901a\u5e38\u306e\u4f7f\u3044\u65b9\u3060\u3051\u3069\uff09\u305d\u306e\u5834\u5408\u3068\u306f\u9055\u3046\u3088\u3068\u3044\u3046\u3053\u3068\u3092\u8a00\u3063\u3066\u308b\u3093\u3060\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u30c6\u30ad\u30b9\u30c8\u306e51\u301c53\u30da\u30fc\u30b8<\/p>\n
\u672c\u6587<\/h3>\n
\u56f34-1\u3067\u793a\u3055\u308c\u308b\u3088\u3046\u306b\u3001\u30d7\u30ed\u30bb\u30b9\u3092\u5207\u308a\u66ff\u3048\u308b\u305f\u3081\u306b\u3001xv6\u306f\u30ed\u30fc\u30ec\u30d9\u30eb\u30672\u7a2e\u985e\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u30b9\u30a4\u30c3\u30c1\u3092\u884c\u3046\u3002
\n\u3072\u3068\u3064\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u73fe\u5728\u306eCPU\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u5207\u308a\u66ff\u3048\u3001\u3082\u3046\u3072\u3068\u3064\u306f\u3001\u305d\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u5207\u308a\u66ff\u3048\u3067\u3042\u308b\u3002
\nxv6\u306f\u3001\u30e6\u30fc\u30b6\u7a7a\u9593\u306e\u30d7\u30ed\u30bb\u30b9\u304b\u3089\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u3078\u76f4\u63a5\u5207\u308a\u66ff\u3048\u308b\u3053\u3068\u306f\u6c7a\u3057\u3066\u3057\u306a\u3044\u3002
\n\u3053\u306e\u3053\u3068\u306f\u3001\u30e6\u30fc\u30b6\u30ab\u30fc\u30cd\u30eb\u306e\u9077\u79fb\uff08\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3084\u5272\u308a\u8fbc\u307f\uff09\u306e\u3084\u308a\u65b9\u306b\u3088\u3063\u3066\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u3078\u306e\u5207\u308a\u66ff\u3048\u3001\u65b0\u3057\u3044\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u30b9\u30a4\u30c3\u30c1\u3001\u305d\u3057\u3066\u30c8\u30e9\u30c3\u30d7\u304b\u3089\u623b\u308b\u3068\u3044\u3046\u4e8b\u3092\u5f15\u304d\u8d77\u3053\u3059\u3002
\n\u3053\u306e\u7bc0\u3067\u306f\u3001\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3068\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b9\u30ec\u30c3\u30c9\u306e\u9593\u306e\u5207\u308a\u66ff\u3048\u306e\u4ed5\u7d44\u307f\u306b\u3064\u3044\u3066\u8aac\u660e\u3059\u308b\u3002<\/p>\n
\"\"<\/a>
\n\u56f34\u22121 \u3042\u308b\u30e6\u30fc\u30b6\u30d7\u30ed\u30bb\u30b9\u304b\u3089\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u3078\u306e\u5207\u308a\u66ff\u3048\u3002\u3053\u306e\u4f8b\u3067\u306f\u3001xv6\u306f\u4e00\u3064\u306eCPU\u3067\u5b9f\u884c\u3055\u308c\u3066\u3044\u308b\u3002\uff08\u3088\u3063\u3066\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30ec\u30c3\u30c9\u3082\u3072\u3068\u3064\u3067\u3042\u308b\uff09<\/p>\n
xv6\u306e\u30d7\u30ed\u30bb\u30b9\u306f\u3069\u308c\u3067\u3082\u3001\u7b2c1\u7ae0\u3067\u898b\u3066\u304d\u305f\u3088\u3046\u306b\u3001\u305d\u308c\u81ea\u8eab\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30bf\u30c3\u30af\u3068\u30ec\u30b8\u30b9\u30bf\u4e00\u5f0f\u3092\u6301\u3064\u3002
\n\u305d\u308c\u305e\u308c\u306eCPU\u306f\u3001\u3069\u3053\u304b\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u3067\u306f\u306a\u304f\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u3092\u5b9f\u884c\u3057\u3066\u3044\u308b\u3068\u304d\u306b\u4f7f\u3046\u305f\u3081\u306e\u500b\u5225\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b9\u30ec\u30c3\u30c9\u3092\u6301\u3064\u3002
\n\u3042\u308b\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u4ed6\u306e\u30b9\u30ec\u30c3\u30c9\u3078\u306e\u5207\u308a\u66ff\u3048\u306f\u3001\u5207\u308a\u66ff\u3048\u5143\u3082\u30b9\u30ec\u30c3\u30c9\u306eCPU\u30ec\u30b8\u30b9\u30bf\u306e\u4fdd\u5b58\u3068\u3001\u5207\u308a\u66ff\u3048\u5148\u306e\u30b9\u30ec\u30c3\u30c9\u306e\u4ee5\u524d\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30ec\u30b8\u30b9\u30bf\u306e\u5fa9\u5143\u3092\u4f34\u3046\u3002
\n%esp\u3068%eip\u304c\u4fdd\u5b58\u3084\u5fa9\u5143\u3055\u308c\u308b\u3068\u3044\u3046\u4e8b\u5b9f\u306f\u3001CPU\u304c\u30b9\u30bf\u30c3\u30af\u3092\u5207\u308a\u66ff\u3048\u3001\u3069\u306e\u30b3\u30fc\u30c9\u304c\u5b9f\u884c\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u5207\u308a\u66ff\u3048\u308b\u3068\u3044\u3046\u4e8b\u3092\u610f\u5473\u3059\u308b\u3002<\/p>\n
swtch\u306f\u30b9\u30ec\u30c3\u30c9\u306b\u3064\u3044\u3066\u306f\u76f4\u63a5\u7684\u306b\u306f\u77e5\u3089\u306a\u3044\u3002
\n\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3068\u547c\u3070\u308c\u308b\u30ec\u30b8\u30b9\u30bf\u4e00\u5f0f\u3092\u4fdd\u5b58\u3057\u5fa9\u5143\u3059\u308b\u3060\u3051\u3067\u3042\u308b\u3002
\n\u30d7\u30ed\u30bb\u30b9\u306bCPU\u3092\u624b\u653e\u3055\u305b\u308b\u3068\u304d\u304c\u6765\u305f\u3068\u304d\u3001\u305d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30ec\u30c3\u30c9\u306f\u3001\u81ea\u8eab\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u4fdd\u5b58\u3057\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306b\u623b\u308b\u305f\u3081\u306bswtch\u3092\u547c\u3076\u3060\u308d\u3046\u3002
\n\u305d\u308c\u305e\u308c\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306f\u3001struct context*\u3068\u3057\u3066\u8868\u73fe\u3055\u308c\u3001\u5dfb\u304d\u8fbc\u307e\u308c\u305f\u30ab\u30fc\u30cd\u30eb\u30b9\u30bf\u30c3\u30af\u4e0a\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30c7\u30fc\u30bf\u69cb\u9020\u3092\u6307\u3059\u30dd\u30a4\u30f3\u30bf\u3067\u3042\u308b\u3002
\nswtch\u306f2\u3064\u306e\u5f15\u6570\u3092\u53d7\u3051\u53d6\u308b\u3002
\nstruct context **old\u3068struct context *new\u3067\u3042\u308b\u3002
\nswtch\u306f\u3001\u73fe\u5728\u306eCPU\u30ec\u30b8\u30b9\u30bf\u306e\u5024\u3092\u30b9\u30bf\u30c3\u30af\u306b\u30d7\u30c3\u30b7\u30e5\u3057\u3001\u305d\u306e\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u3092*old\u306b\u4fdd\u5b58\u3059\u308b\u3002
\n\u305d\u3057\u3066swtch\u306f\u3001new\u304b\u3089%esp\u306b\u30b3\u30d4\u30fc\u3057\u3001\u4ee5\u524d\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30ec\u30b8\u30b9\u30bf\u3092\u53d6\u308a\u51fa\u3057\u3001\u305d\u3057\u3066\u623b\u308b\u3002<\/p>\n
proc.h\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308bcontext\u69cb\u9020\u4f53<\/p>\n
\/\/ Saved registers for kernel context switches.\r\n\/\/ Don't need to save all the segment registers (%cs, etc),\r\n\/\/ because they are constant across kernel contexts.\r\n\/\/ Don't need to save %eax, %ecx, %edx, because the\r\n\/\/ x86 convention is that the caller has saved them.\r\n\/\/ Contexts are stored at the bottom of the stack they\r\n\/\/ describe; the stack pointer is the address of the context.\r\n\/\/ The layout of the context matches the layout of the stack in swtch.S\r\n\/\/ at the "Switch stacks" comment. Switch doesn't save eip explicitly,\r\n\/\/ but it is on the stack and allocproc() manipulates it.\r\nstruct context {\r\n  uint edi;\r\n  uint esi;\r\n  uint ebx;\r\n  uint ebp;\r\n  uint eip;\r\n};<\/pre>\n
swtch.S<\/p>\n
# Context switch\r\n#\r\n#   void swtch(struct context **old, struct context *new);\r\n# \r\n# Save current register context in old\r\n# and then load register context from new.\r\n\r\n.globl swtch\r\nswtch:\r\n  movl 4(%esp), %eax\r\n  movl 8(%esp), %edx\r\n\r\n  # Save old callee-save registers\r\n  pushl %ebp\r\n  pushl %ebx\r\n  pushl %esi\r\n  pushl %edi\r\n\r\n  # Switch stacks\r\n  movl %esp, (%eax)\r\n  movl %edx, %esp\r\n\r\n  # Load new callee-save registers\r\n  popl %edi\r\n  popl %esi\r\n  popl %ebx\r\n  popl %ebp\r\n  ret<\/pre>\n
Instead of following the scheduler into swtch, let\u2019s instead follow our user process back in.\uff08\u3053\u3053\u8a33\u304c\u5206\u304b\u3089\u306a\u3044\uff09<\/del>
\n\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u304b\u3089swtch\u3078\u306e\u6d41\u308c\u3092\u8ffd\u3046\u4ee3\u308f\u308a\u306b\u3001\u30e6\u30fc\u30b6\u30fc\u30d7\u30ed\u30bb\u30b9\u304c\u623b\u3063\u3066\u304f\u308b\u6d41\u308c\u3092\u8ffd\u3063\u3066\u307f\u3088\u3046\u3002<\/ins>
\n\u305d\u308c\u305e\u308c\u306e\u5272\u308a\u8fbc\u307f\u306e\u6700\u5f8c\u306btrap\u95a2\u6570\u304cyield\u95a2\u6570\u3092\u547c\u3076\u53ef\u80fd\u6027\u306b\u3064\u3044\u3066\u3001\u6211\u3005\u306f\u7b2c2\u7ae0\u3067\u898b\u305f\u3002
\n\u540c\u69d8\u306byield\u95a2\u6570\u306f\u3001\u73fe\u5728\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092proc->context\u3078\u4fdd\u5b58\u3057\u3001\u4ee5\u524d\u306bcpu->scheduler\u306b\u4fdd\u5b58\u3055\u308c\u305f\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3078\u5207\u308a\u66ff\u3048\u308b\u305f\u3081\u306eswtch\u3092\u547c\u3076sched\u95a2\u6570\u3001\u3092\u547c\u3076\u3002<\/p>\n
proc.c\u306esched\u95a2\u6570\u3068yield\u95a2\u6570<\/p>\n
\/\/ Enter scheduler.  Must hold only ptable.lock\r\n\/\/ and have changed proc->state.\r\nvoid\r\nsched(void)\r\n{\r\n  int intena;\r\n\r\n  if(!holding(&ptable.lock))\r\n    panic("sched ptable.lock");\r\n  if(cpu->ncli != 1)\r\n    panic("sched locks");\r\n  if(proc->state == RUNNING)\r\n    panic("sched running");\r\n  if(readeflags()&FL_IF)\r\n    panic("sched interruptible");\r\n  intena = cpu->intena;\r\n  swtch(&proc->context, cpu->scheduler);\r\n  cpu->intena = intena;\r\n}\r\n\r\n\/\/ Give up the CPU for one scheduling round.\r\nvoid\r\nyield(void)\r\n{\r\n  acquire(&ptable.lock);  \/\/DOC: yieldlock\r\n  proc->state = RUNNABLE;\r\n  sched();\r\n  release(&ptable.lock);\r\n}<\/pre>\n
swtch\u306f\u3001%eax\u30ec\u30b8\u30b9\u30bf\u3068%edx\u30ec\u30b8\u30b9\u30bf\u3078\u81ea\u8eab\u306e\u5f15\u6570\u3092\u8aad\u307f\u8fbc\u3080\u4e8b\u304b\u3089\u958b\u59cb\u3059\u308b\u3002
\n\u3053\u308c\u306f\u5fc5\u8981\u306a\u51e6\u7406\u3067\u3042\u308b\u3002
\n\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u3092\u5909\u66f4\u3059\u308b\u3068\u3001\u3082\u306f\u3084%esp\u7d4c\u7531\u3067\u5f15\u6570\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u3053\u3068\u304c\u51fa\u6765\u306a\u304f\u306a\u308b\u304b\u3089\u3067\u3042\u308b\u3002
\n\u305d\u3057\u3066swtch\u306f\u3001\u73fe\u5728\u306e\u30b9\u30bf\u30c3\u30af\u4e0a\u306bcontext\u69cb\u9020\u4f53\u3092\u4f5c\u308b\u305f\u3081\u3001\u30ec\u30b8\u30b9\u30bf\u306e\u72b6\u614b\u3092\u30d7\u30c3\u30b7\u30e5\u3059\u308b\u3002
\n\u547c\u3073\u51fa\u3055\u308c\u308b\u5074\u3067\u4fdd\u5b58\u3055\u308c\u308b\u30ec\u30b8\u30b9\u30bf\u3060\u3051\u4fdd\u5b58\u3055\u308c\u308b\u5fc5\u8981\u304c\u3042\u308b\u3002
\nx86\u306e\u6163\u7fd2\u3067\u306f\u3001\u305d\u308c\u3089\u306f%ebp, %ebx, %esi, %ebp, %esp\u3067\u3042\u308b\u3002
\nswtch\u306f\u3001\u6700\u521d\u306e4\u3064\u3092\u76f4\u63a5\u30d7\u30c3\u30b7\u30e5\u3059\u308b\u3002\uff08# Save old callee\u2212save registers\u306e\u3068\u3053\u308d\uff09
\n\u9593\u63a5\u7684\u306bstruct context*\u3068\u3057\u3066*old\u306b\u66f8\u304d\u8fbc\u3080\u305f\u3081\u306b\u6700\u5f8c\u306e\u3082\u306e\u3092\u4fdd\u5b58\u3059\u308b\u3002\uff08movl %esp, (%eax)\u306e\u3068\u3053\u308d\uff09
\n\u3082\u3046\u3072\u3068\u3064\u91cd\u8981\u306a\u30ec\u30b8\u30b9\u30bf\u304c\u3042\u308b\u3002
\n\u30d7\u30ed\u30b0\u30e9\u30e0\u30ab\u30a6\u30f3\u30bf%eip\u306f\u3001swtch\u3092\u547c\u3073\u51fa\u3057\u305fcall\u547d\u4ee4\u306b\u3088\u3063\u3066\u4fdd\u5b58\u3055\u308c\u3001%ebp\u306e\u3061\u3087\u3046\u3069\u3059\u3050\u4e0a\u4f4d\u306e\u30b9\u30bf\u30c3\u30af\u306b\u3042\u308b\u3002
\n\u53e4\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u304c\u4fdd\u5b58\u3055\u308c\u305f\u3089\u3001swtch\u306f\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5fa9\u5143\u3059\u308b\u6e96\u5099\u3092\u3059\u308b\u3002
\n\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306e\u30dd\u30a4\u30f3\u30bf\u3092\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u306b\u79fb\u52d5\u3059\u308b\u3002\uff08movl %edx, %esp\u306e\u3068\u3053\u308d\uff09
\n\u65b0\u3057\u3044\u30b9\u30bf\u30c3\u30af\u306f\u3001swtch\u304c\u3061\u3087\u3046\u3069\u3044\u307e\u51e6\u7406\u3057\u305f\u3070\u304b\u308a\u306e\u53e4\u3044\u30b9\u30bf\u30c3\u30af\u3068\u540c\u3058\u5f62\u5f0f\u3067\u3042\u308a\u3001\uff08\u524d\u56de\u306eswtch\u306e\u547c\u3073\u51fa\u3057\u3067\u306f\u305d\u306e\u65b0\u3057\u3044\u30b9\u30bf\u30c3\u30af\u306f\u53e4\u3044\u30b9\u30bf\u30c3\u30af\u3060\u3063\u305f\uff09swtch\u306f\u9006\u306e\u624b\u9806\u3067\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5fa9\u5143\u3059\u308b\u3002
\n%edi, %esi, %ebx, %ebp\u3092\u30dd\u30c3\u30d7\u3057\u3001\u305d\u3057\u3066\u623b\u308b\u3002\uff08# Load new callee\u2212save registers\u306e\u3068\u3053\u308d\uff09
\nswtch\u306f\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u3092\u5909\u66f4\u3059\u308b\u306e\u3067\u3001\u5fa9\u5143\u3055\u308c\u305f\u5024\u3068\u623b\u308a\u5148\u306e\u547d\u4ee4\u30a2\u30c9\u30ec\u30b9\u306f\u3001\u65b0\u3057\u3044\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306e\u3082\u306e\u3068\u306a\u308b\u3002<\/p>\n
\u6211\u3005\u306e\u4f8b\u3067\u306f\u3001sched\u306fCPU\u3054\u3068\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3067\u3042\u308bcpu->scheduler\u3078\u5207\u308a\u66ff\u3048\u308b\u305f\u3081\u306bswtch\u3092\u547c\u3093\u3060\u3002
\n\u305d\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306f\u3001scheduler\u95a2\u6570\u306b\u3088\u308bswtch\u306e\u547c\u3073\u51fa\u3057\u306b\u3088\u3063\u3066\u3059\u3067\u306b\u4fdd\u5b58\u3055\u308c\u305f\u3082\u306e\u3067\u3042\u308b\u3002
\n\u6211\u3005\u304c\u8ffd\u8de1\u3057\u3066\u3044\u308bswtch\u304b\u3089\u623b\u3063\u305f\u3068\u304d\u3001sched\u3067\u306f\u306a\u304fscheduler\u3078\u623b\u308a\u3001\u305d\u3057\u3066\u30b9\u30bf\u30c3\u30af\u30dd\u30a4\u30f3\u30bf\u306f\u3001initproc\u306e\u30ab\u30fc\u30cd\u30eb\u30b9\u30bf\u30c3\u30af\u3067\u306f\u306a\u304f\u3001\u73fe\u5728\u306eCPU\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306e\u30b9\u30bf\u30c3\u30af\u3092\u6307\u3059\u72b6\u614b\u306b\u306a\u3063\u3066\u3044\u308b\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
\u6fc3\u3044\u7bc0\u3067\u3057\u305f\u3002
\n\u307e\u3068\u3081\u308b\u3068\u3001
\n\u30d7\u30ed\u30bb\u30b9\u3092\u5207\u308a\u66ff\u3048\u308b\u969b\u306f\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306b\u4e00\u65e6\u5207\u308a\u66ff\u3048\u3066\u304b\u3089\u3001\u76ee\u7684\u306e\u30d7\u30ed\u30bb\u30b9\u306b\u5207\u308a\u66ff\u3048\u308b\u3002
\n\u5207\u308a\u66ff\u3048\u51e6\u7406\u306e\u30b3\u30a2\u306fswtch\u3067\u3042\u308b\u3002
\nswtch\u3067\u306f\u3001\u5207\u308a\u66ff\u3048\u5143\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u4fdd\u5b58\u3057\u3066\u3001\u5207\u308a\u66ff\u3048\u5148\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5fa9\u5143\u3059\u308b\u3002
\n\u3063\u3066\u3068\u3053\u308d\u3067\u3059\u304b\u306d\u3002<\/p>\n
yield\u306e\u8aac\u660e\u306e\u3068\u3053\u308d\u3067\u306f\u8a33\u304c\u3088\u304f\u5206\u304b\u3089\u306a\u3044\u6587\u304c\u3042\u308a\u307e\u3059\u304c\u3001\u30bd\u30fc\u30b9\u3092\u898b\u308b\u3068trap\u95a2\u6570\u306e\u6700\u5f8c\u306b\u30bf\u30a4\u30de\u5272\u308a\u8fbc\u307f\u3060\u3063\u305f\u3089yield\u3092\u5b9f\u884c\u3059\u308b\u3068\u3044\u3046\u30b3\u30fc\u30c9\u304c\u3042\u308a\u3001\u305d\u3053\u304c\u6642\u5206\u5272\u306e\u30ad\u30e2\u3068\u306a\u308b\u90e8\u5206\u304b\u3068\u601d\u3044\u307e\u3059\u3002
\n\u305d\u3053\u3067\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u30b9\u30ec\u30c3\u30c9\u3078\u5207\u308a\u66ff\u308f\u308a\u3001\u30b9\u30b1\u30b8\u30e5\u30fc\u30e9\u306fRUNNABLE\u306a\u30d7\u30ed\u30bb\u30b9\u3092\u63a2\u3057\u3066\u305d\u308c\u306b\u5207\u308a\u66ff\u3048\u308b\u3001\u3068\u3044\u3046\u51e6\u7406\u304c\u884c\u308f\u308c\u308b\u306f\u305a\u3067\u3059\u3002<\/p>\n
\u6700\u5f8c\u306einitproc\u306a\u3093\u3061\u3083\u3089\u306e\u3068\u3053\u308d\u306f\u3001\u7b2c1\u7ae0\u306eCode: Running a process\u3067\u8aac\u660e\u304c\u3042\u3063\u305f\u90e8\u5206\u3067\u3059\u3002
\nswtch\u306f\u8d77\u52d5\u4e2d\u306e\u7279\u5225\u306a\u51e6\u7406\u3067\u3082\u4f7f\u308f\u308c\u308b\u306e\u3067\u3059\u304c\u3001\u5358\u306b\u4eca\u56de\u306f\uff08\u3068\u3044\u3046\u304b\u3053\u3061\u3089\u304c\u901a\u5e38\u306e\u4f7f\u3044\u65b9\u3060\u3051\u3069\uff09\u305d\u306e\u5834\u5408\u3068\u306f\u9055\u3046\u3088\u3068\u3044\u3046\u3053\u3068\u3092\u8a00\u3063\u3066\u308b\u3093\u3060\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[405],"class_list":["post-1547","post","type-post","status-publish","format-standard","hentry","category-tech","tag-xv6"],"_links":{"self":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1547","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/comments?post=1547"}],"version-history":[{"count":0,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1547\/revisions"}],"wp:attachment":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/media?parent=1547"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/categories?post=1547"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/tags?post=1547"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}