A new direction for Linux for gadgets

TalkBack 4 of 7:

Next »

« Previous

• Thread View
• Flat View

There are hardware interupts and software interupts that must work together

When a hardware interupt is triggered and the OS is written to respond immediately, then all other processes can be pre-empted to run whatever process needs runnning.

But what if three hardware interupts are triggered? Which process do you run? On a good, true multithreaded/multitasking CPU you might be able to run all three but what if two of those three need to use the LPT1 and two of the three needs to use COM1 and two of the three need to use standard out? Now hardware interupts become meaningless without software interupts --which, of course, must be mindfull of hardware interupts.

Bear in mind also, that any other process must be pre-empted for these three. If you are running mission-critical apps, they better not be on this box. Now, with CPU overkill, let the three processes duke it out through whatever arbitration protocol you have and they all will finish their tasks in adequate time. Dedicate one processor in an SMP box or have separate boxes for each process and you fare even better.

But suppose you are running a nuclear plant and any one given plant process is dependent on how all the other processes are running --should we lower/raise the rods, are we running too hot/cold, do we need more/less water, is our power load high/low, are our fuel cells fresh/exausted, is radiation contained/compromised-- and all these mission-critical processes have to talk to each other? Which one gets pre-empted? Who gets to talk first/last? Who gets dibs on COM1?

Hence hardware interupts alone is not the issue. Of course such issues are not in everyday computing needs but this hard real-time kernel is not for everyday computing needs either. This issue does not affect most of us but for those whom it may affect, it is good to know that choices are coming.

Is your question answered?

Posted by: The King's Servant   Posted on: 10/12/04 You are currently: a Guest | Members login | Terms of Use

Alert moderator to an offensive message

Subscribe to this discussion via Email or RSS

SponsoredWhite Papers, Webcasts, and Downloads

• The Impact of Virtualization Software on Operating Environments VMware Today's use of virtualization technology allows IT professionals to ... Download Now
• Open Standards Technologies Provide the Ingredients for Delivering Security Across the Papa Gino's Enterprise Dell Papa Gino's Holdings Corporation founded by the entrepreneur operates one ... Download Now
• Five Steps to Determine When to Virtualize YourServers VMware Server virtualization isn't just for big companies. Entry-level ... Download Now