Exploiting edge-triggered event notification while preserving legacy level-triggered semantics
Publication Date: 2014-May-27
The IP.com Prior Art Database
A method for exploiting edge triggered event notification while preserving legacy level triggered semantics is disclosed.
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Exploiting edge-triggered event notification while preserving legacy level -triggered semantics
Disclosed is a method for exploiting edge triggered event notification while preserving legacy level triggered semantics.
Legacy applications expect the semantics of poll(), which are also provided by epoll in its level triggered mode to work properly. An example is the case of read notification, where partial reads are guaranteed to result in future read notification to "drive" the remaining read activity. Servers scale much better to many clients by using epoll instead of poll, but leave some performance benefits on the table by using level triggered mode to maintain compatibility. The issue is the cost of adjusting registered event notification, typically between interest in readability and in write-ability. In edge triggered mode, it is practical to leave this registration constant, which improves performance at the cost of incompatibility. For example, in the partial read case mentioned above, edge triggered mode will not provide a fresh indication of readability. By judiciously using poll() in combination with edge triggered epoll, it is possible to gain the performance advantages of constant registration while retaining compatibility with an application expecting level triggered semantics. All notifications are requested from epoll in edge-triggered mode. This registration is held constant. Notifications which are not currently requested by the application are...