• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

What is USB - Iso queue, non iso queue

A USB peripheral can request one of several data transfer modes from the PC, which will then schedule it's data most appropriately.
Control mode: low bandwidth, any latency
Interrupt mode: low bandwidth, minimum latency (e.g. keyboard, mouse)
Bulk mode: High bandwidth, any latency (e.g. hard drive, flash)
Isochronous mode: Predictable high bandwidth for streaming, low latency (e.g. microphone, speaker, webcam, video capture unit).

One of the advancements in USB was the development of a scheduler in the USB controller - this allowed the PC to batch up a number of transmit/receive requests in the controller - and the controller would then hold the individual requests in a queue executing them as needed. Optimising overall performance and minimizing CPU usage.

Because of the unique requirements of each of the 4 USB modes - they had to go into 2 queues:
The periodic queue is optimised so that requests don't miss their maximum latency deadline. Isochronous requests (and interrupt requests) go into the periodic queue.

The asynchronous queue is used for bulk data and control data and is optimised for maximum bandwidth (they are non-isochronous).

I would interpret "Iso queue" as meaning the periodic scheduler's queue (consisting of isochronous requests and interrupt requests), and "non-iso queue" as meaning the async scheduler's queue (consisting of bulk and control data).
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top