What are completion ports?

What are completion ports?

I/O completion ports provide an efficient threading model for processing multiple asynchronous I/O requests on a multiprocessor system. When a process creates an I/O completion port, the system creates an associated queue object for requests whose sole purpose is to service these requests.

What is a completion port thread?

The CLR ThreadPool has two types of threads – “Worker” and “I/O Completion Port” (aka IOCP) threads. These threads are also used by various components in the CLR when work needs to happen on a background thread. IOCP threads are used when asynchronous IO happens (e.g. reading from the network).

What is overlapped I o operation?

Overlapped I/O is a name used for asynchronous I/O in the Windows API. It was introduced as an extension to the API in Windows NT. Utilizing overlapped I/O requires passing an OVERLAPPED structure to API functions that normally block, including ReadFile() , WriteFile() , and Winsock’s WSASend() and WSARecv() .

What is Getqueuedcompletionstatus?

dwMilliseconds. The number of milliseconds that the caller is willing to wait for a completion packet to appear at the completion port. If a completion packet does not appear within the specified time, the function times out, returns FALSE, and sets *lpOverlapped to NULL.

What does IOCP mean?

Input/output completion port (IOCP) is an API for performing multiple simultaneous asynchronous input/output operations in Windows NT versions 3.5 and later, AIX and on Solaris 10 and later. An input/output completion port object is created and associated with a number of sockets or file handles.

How do I change the IOCP in AIX?


  1. Log in to the server as root.
  2. Enter the following command:
  3. Select Change / Show Characteristics of I/O Completion Ports.
  4. At system restart, change the configured state from Defined to Available .
  5. Make the state change effective by either rebooting the system or entering the cfgmgr command.

What means overlapped?

1 : to extend over or past and cover a part of The roof shingles overlap each other. 2 : to have something in common with Baseball season overlaps the football season in September. intransitive verb. 1 : to occupy the same area in part The two towns overlap. 2 : to have something in common Some of their duties overlap.

What is the meaning of overlapped CPU?

The 1130 system permits input/output devices to operate simultaneously; that is, to overlap their operation with other functions of the CPU. Overlapping I/O operations provides increased data throughput and more efficient utilization of the central processing unit.

What is WSARecv?

The WSARecv function is used on connected sockets or bound connectionless sockets specified by the s parameter and is used to read incoming data. The socket’s local address must be known. For server applications, this is usually done explicitly through bind or implicitly through accept or WSAAccept.

How do I enable IOCP?

To enable IOCP, set IOCP to Available using the following procedure:

  1. Log in as root and run the following command:
  2. Select Change / Show Characteristics of I/O Completion Ports.
  3. Change configured state at system restart from Defined to Available .
  4. Run the lsdev command to confirm the IOCP status is set to Available :

How do I know if IOCP is enabled in Linux?

If the IOCP port status is Defined , perform the following steps: Log in to the server as root. Select Change / Show Characteristics of I/O Completion Ports. At system restart, change the configured state from Defined to Available .

Can genes be overlapping?

Overlapping genes are relatively common in DNA and RNA viruses. There are several examples in bacterial and eukaryotic genomes, but, in general, overlapping genes are quite rare in organisms other than viruses. There have been a few reports of overlapping genes in mammalian genomes.