Contents
- 1 What is a Linux queue?
- 2 How does Linux networking work?
- 3 What is the maximum size of message queue?
- 4 How do I see message queue in Linux?
- 5 What is the use of NIC?
- 6 Where are IP packets queued on the Linux network stack?
- 7 Why is there a queue between VoIP packets?
- 8 Why does the IP stack have a driver queue?
What is a Linux queue?
In the Linux operating system (prior to kernel 2.6. 23), each CPU in the system is given a run queue, which maintains both an active and expired array of processes. Each array contains 140 (one for each priority level) pointers to doubly linked lists, which in turn reference all processes with the given priority.
How does Linux networking work?
The simplest form of networking is a connection between two hosts. On each end, an application gets a socket, makes the transport layer connection, and then sends or receives packets. In Linux, a socket is actually composed of two socket structures (one that contains the other).
What is the Linux network stack?
In the Linux operating system, the network stack is useful to communicate the application with the physical network devices. The network stack is divided into multiple layers. There are different network layers. While communicating with different devices, the physical layer comes in the picture.
What is the maximum size of message queue?
Figure 15.26. System limits that affect message queues
| Description | Typical values | |
|---|---|---|
| FreeBSD 5.2.1 | Solaris 9 | |
| Size in bytes of largest message we can send | 16,384 | 2,048 |
| The maximum size in bytes of a particular queue (i.e., the sum of all the messages on the queue) | 2,048 | 4,096 |
| The maximum number of messages queues, systemwide | 40 | 50 |
How do I see message queue in Linux?
Use the Unix command ipcs to get a list of defined message queues, then use the command ipcrm to delete the queue.
What is Softirq in Linux?
As a matter of fact, the term “softirq,” which appears in the kernel source code, often denotes both kinds of deferrable functions. Another widely used term is interrupt context : it specifies that the kernel is currently executing either an interrupt handler or a deferrable function.
What is the use of NIC?
The Role of the NIC The network interface card (NIC) or network card is the hardware device most essential to establishing communication between computers.
Where are IP packets queued on the Linux network stack?
This article aims to explain where IP packets are queued on the transmit path of the Linux network stack, how interesting new latency-reducing features, such as BQL, operate and how to control buffering for reduced latency. Figure 1. Simplified High-Level Overview of the Queues on the Transmit Path of the Linux Network Stack
Why is Queueing important in the Linux stack?
Queueing in the Linux Network Stack. Packet queues are a core component of any network stack or device. They allow for asynchronous modules to communicate, increase performance and have the side effect of impacting latency.
Why is there a queue between VoIP packets?
Interactive applications like VoIP or gaming typically emit small packets at fixed intervals that are latency-sensitive, while a high-bandwidth data transfer generates a higher packet rate and larger packets. This higher packet rate can fill the queue between interactive packets, causing the transmission of the interactive packet to be delayed.
Why does the IP stack have a driver queue?
The reason the driver queue exists is to ensure that whenever the system has data to transmit, the data is available to the NIC for immediate transmission. That is, the driver queue gives the IP stack a location to queue data asynchronously from the operation of the hardware.