在页面上发出 asnyc I/O
我想知道在已换出的页面上发出异步读取操作的正确方法是什么。一旦完成，有没有办法执行发生的回调，以便我可以在该页面上执行一些逻辑？
I was wondering what the correct way of issuing an asynchronous read operation on a page that has been swapped out is. And once this is done is there a way to execute a callback that happens so that I can execute some logic with that page?
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madvise(start_address, length, MADV_WILLNEED)会做到这一点。回调实际上并不存在，但如果需要，您可以使用
mincore系统调用轮询状态快照。请注意，相反的提示
MADV_DONTNEED不会不按照您的想法执行操作，msync也不会执行此操作。文档在撒谎。在 Linux 下，没有一种非设计性的方式来启动异步回写（尽管文档是这么说的）。您可以选择无操作、丢弃页面、同步写回或异步写回并清除缓存。
madvise(start_address, length, MADV_WILLNEED)will do that.A callback does not really exist, though you can poll a snapshot of the status with the
mincoresyscall, if you want.Note that the opposite hint
MADV_DONTNEEDdoes not do what you think, nor doesmsync. The documentation is lying.There is no non-broken-by-design way to start asynchronous writeback under Linux (although the documentation says so). You can choose between no-op, throwing pages away, synchronous writeback, or asynchronous writeback with purging the cache.