1 / 2

xcybercloud.blogspot/2009/01/asychronous-io-model-on-windows.html

http://xcybercloud.blogspot.com/2009/01/asychronous-io-model-on-windows.html.

jacqui
Download Presentation

xcybercloud.blogspot/2009/01/asychronous-io-model-on-windows.html

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. http://xcybercloud.blogspot.com/2009/01/asychronous-io-model-on-windows.htmlhttp://xcybercloud.blogspot.com/2009/01/asychronous-io-model-on-windows.html - Multi-threading is supported through thread library- I/O multiplexing is supported by select(), WSAAsyncSelect(), WSAEventSelect()- Async Polling/Async Waiting is supported by means of Overlapped I/O- Async Callback model is supported by means of Alertable I/O- Async Queuing is supported by means of I/O Completion Port

  2. - Scalable Asynchronous I/O Models　　In Async Model, I/O operation call returns immediately after being issued and code that follows will get executed. The various models differs only on how to get I/Ocompletion notification:1. Polling - Use various polling function (such asHasOverlappedIoCompleted() on Windows) to poll whether some pending Async I/O is completed2. Callback - Kernel will call some user provided call back functions when some i/o operations are completed.3. Waiting - The OS kernel will signal some kernel event objects when i/o operations are completed. Application code just waits on these events to get completion notification.4. Queuing - Kernel will place some information packet into a Queue (such as I/O Completion Port on Windows) when I/O operations completed. Client code should check that Queue for completion information.Another advantage of Async I/O is that it reduces memory copy cost. Other I/O models need copy data(for send/receive) in system buffer from/to application buffer. In Async I/O, system knows the receiving/sending buffer when the io request is issued, so I can use it directly, no need to do memory copy between system space and user space.

More Related