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Thu, 04 Jan 2007

AIO (sub) state machine has been completed.


It is small subsystem, which lives in kernel/kevent/kevent_aio.c file, which allows to queue and asynchronously invoke callbacks, which are intended to populate pages into VFS cache, send data to the destination socket, copy data to/from userspace and so on.

Real working callbacks itself are not implemented yet.

I will only implement three of them - open file by filename, populate file's pages into VFS cache, send pages to destination socket.
Probably will also add writing page to userspace.
This set will allow to implement aio_sendfile() as sequence of that callbacks - open file by file path, then populate its pages into VFS cache in some chunks or one-by-one and eventually send them to the destination socket.
There is a problem of the order of sending one page and populating its neighbour though, since having the whole VFS cache filled with locked pages from one file is not a good idea, but locking is required to allow sending itself - so page would not be swapped out. But I will either stop further populating until pages are sent, or will not firgure this out at all - depending on results from initial implementation.
Each subtask above - i.e. each callback, is an elementary chunk, which will be handled by kevent. Completeness of the whole task will be handled by kevent too.

/devel/kevent/aio :: Link / Comments (0)

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