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My system is a notebook system with an AMD A10 5750m CPU, R9 M290X GPU, 8GB, 1TB. I’ve noticed a process that is always active called “System Interrupts,” in this moment, it consumes in average 1.5% of CPU.

I’ve searched everywhere, but I have not found anything about this process. I’ve found people who have the process consuming extremely high values of CPU, which is not my case. Is it normal? Will it be active all the time, consuming (even) a minimal part of CPU?

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"System interrupts" is not a process in the traditional sense, but is present to try to explain to the user that the computer is spending 1.5% of its CPU resources processing interrupt requests. Interrupts occur below the OS level, so they are not associated with any particular process.

Interrupts (IRQs) exist so that the hardware components of your system can tell the CPU things like "an error occurred", or "the data you requested is now available", or "this device would like to send data". Any time a device or piece of software needs to tell the CPU something about the task it's performing, or needs to instruct the CPU to do something, it raises an Interrupt, which the CPU receives and handles. When this happens, the CPU immediately stops what it is doing such that it processes the interrupt.

When viewed as a process, another related item are Deferred Procedure Calls (DPCs), which are OS functions called either directly or indirectly in response to a raised interrupt, in an asynchronous manner. By adding the System Interrupts and DPC processing together, you can generally estimate the amount of resources in use responding to IRQ handling.

There are good interrupts and bad ones. If you are spending a lot of time on interrupt processing, there is a good probability that at least one piece of hardware is failing. On the other hand, lots of hardware use IRQs for timing and other valuable purposes. For instance, the PCI bus uses IRQs to control what device is using the bus at any given instant, so that every device shares the bus efficiently.

At 1.5%, everything sounds normal to me.

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    Thanks for your answer. What percentage of consumption should worry me? If I'd have a problem, how can I know what piece of Hardware is failing? – Daniel Dec 15 '14 at 6:24
  • really depends on the frequency of your CPU. I've had systems that just sat at 1.5, and others at less than 0.10 - 0.20. I'd really worry if you were using more than 10% on a modern machine. – Frank Thomas Dec 15 '14 at 6:28
  • My CPU runs at 2.5ghz. It's weird, sometimes it's on 1,5% (as I've said: Average) and for example it's now in 0,3%, but I've seen it in 5%. I will take the JakeGould's advice and I won't overthink this anymore... my PC is perfectly fine :) And now I know a little bit more about it. Thanks!! – Daniel Dec 15 '14 at 6:31
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    for the most part, you don't, unless there is a hardware problem that you diagnose and repair. you could avoid USB volumes for hard disks (instead installing the disk on a SATA port), as USB uses interrupts for sharing the bus, but other than that kind of thing, unless there is somthing wrong, you need the interrupts you are getting. They are not a user configurable thing, other than perhaps the Addresses each device uses, which is all that you could do 20 years ago. – Frank Thomas Dec 15 '14 at 14:40
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    @Devilathor, Not much. The whole architecture of computers is based on interrupts and forcingly reducing their use by CPU (if even possible) would simply hang or slow down your whole system. The only safe way to reduce the number of interrupts is to reduce the number of hardware parts sending interrupts to the CPU. For that you can remove/unplug/turn off all non necessary hardware and see if that makes a difference. If some hardware are not removable, look for settings which would trigger less 'refresh' from them (stand-by mode if possible). – Hoki Dec 15 '14 at 14:44
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“System Interrupts”—also known as “Interupts” and “IRQs”—are operating system level processes that manage how hardware communicates with your system. As explained here on Wikipedia:

In systems programming, an interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention. An interrupt alerts the processor to a high-priority condition requiring the interruption of the current code the processor is executing. The processor responds by suspending its current activities, saving its state, and executing a function called an interrupt handler (or an interrupt service routine, ISR) to deal with the event. This interruption is temporary, and, after the interrupt handler finishes, the processor resumes normal activities.

So it is a necessary part of your core system setup. And if the CPU usage shoots through the roof, it simply means there is some issue with your system communicating to hardware.

  • Thanks. How can I monitor what events are causing these interruptions? If there's something wrong, there should be a way to learn what's going on, isn't it? – Daniel Dec 15 '14 at 6:20
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    Not 100% sure on Windows machines. But I have never heard of any Windows admins I have worked with care about that much. You might be overthinking this. More details from Microsoft. technet.microsoft.com/en-us/library/cc940374.aspx – JakeGould Dec 15 '14 at 6:23
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    you generally cant view interrupt info in an OS, because they occur below the OS level. its really not a huge concern unless your CPU is really high for IRQ or DPC processing. – Frank Thomas Dec 15 '14 at 6:28
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    @Devilathor Well, part of the reason I am not so sure about interrupts anymore is because the last I really dealt with them was—seriously—back in 1992 when I was first doing I.T. work on 486 machines. And setting IRQs sometimes meant a combo of BIOS and physical jumper adjustments. So I think my brain has no use for understanding that stuff nowadays when all of that is really behind the scenes on most systems. – JakeGould Dec 15 '14 at 8:28
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    IRQs are seriously for operations that are not pertinent to a user. I don't care when my CPU performs a context-switch to run a different thread while a DMA operation for the paused thread is waiting for an asynchronous callback IRQ to indicate that the data is ready for use. That kind of thing happens literally a million times a second. – Frank Thomas Dec 15 '14 at 14:45

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