带有MAP_POPULATE的Linux mmap(),手册页似乎给出了错误的信息

概述在我看来,MAP_POPULATE不仅仅适用于私有映射,与手册页所说的相反： MAP_POPULATE (since Linux 2.5.46) Populate (prefault) page tables for a mapping. For a file mapping, this causes read-ahead on the file. Later accesses to the ma 在我看来,MAP_POPulATE不仅仅适用于私有映射,与手册页所说的相反：

MAP_POPulATE (since Linux 2.5.46) Populate (prefault) page tables for
a mapPing. For a file mapPing,this causes read-ahead on the file.
Later accesses to the mapPing will not be blocked by page faults.
MAP_POPulATE is only supported for private mapPings since linux
2.6.23.

基于我对mmap.c的linux内核源的粗略检查,看起来MAP_POPulATE与versions going back as far as 2.6.34中的MAP_PRIVATE完全没有关系.

以下是3.14内核实现中mmap.c的最新代码的摘录：

...1364         addr = mmap_region(file,addr,len,vm_flags,pgoff);1365         if (!IS_ERR_VALUE(addr) &&1366             ((vm_flags & VM_LOCKED) ||1367              (flags & (MAP_POPulATE | MAP_NONBLOCK)) == MAP_POPulATE))1368                 *populate = len;1369         return addr;...

我的观察错了吗？

解决方法@H_301_32@ 自您提出问题后,措辞已更新：

Before: MAP_POPulATE is only supported for private mapPings since linux 2.6.23.After:  MAP_POPulATE is supported for private mapPings only since linux 2.6.23.

换句话说,您可以将MAP_POPulATE用于私有映射,但至少需要linux 2.6.23.

希望这能澄清它！

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