Timeline for How is it possible for a process to use less than 100% CPU?
Current License: CC BY-SA 4.0
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| Sep 25, 2019 at 5:08 | comment | added | slebetman | @Fishy Generally, I/O heavy programs that does a lot of reads and writes typically use only around 0.1% CPU usage of a single core. This is because the majority of the program is stuck waiting for data to arrive from disk/network therefore the OS will notice this and stop running that program until the data arrives. Programs that use 100% CPU tend to be ones that does not do a lot of reads and writes (or delegate them to a separate thread) but instead does a lot of math (for example rendering a scene in a 3D movie) | |
| Sep 23, 2019 at 19:00 | history | edited | Doc Brown | CC BY-SA 4.0 |
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| Sep 20, 2019 at 8:38 | history | edited | Doc Brown | CC BY-SA 4.0 |
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| Sep 19, 2019 at 19:22 | comment | added | Doc Brown | @Fishy: as I wrote, in reality, things are more complicated. A process may get 100% CPU usage, but only if it contains at least as many threads as CPU cores in the machine, and only if these threads don't wait for events. A program which does a lot "read and writes (to a storage device, for example), does usually this - it sends data to some device, or asks to get some data from there, and then waits for the device - this way, it won't get necessarily more CPU usage by gettings its priority increased. | |
| Sep 19, 2019 at 19:17 | vote | accept | Fishy | ||
| Sep 19, 2019 at 19:14 | comment | added | Fishy | So then, for a process to have a 100% usage, it would have to be assigned a higher priority by the operating system? For example, in Windows, it would see that a program is using a lot of reads and writes, then assign it a higher priority so that it can use more cycles? | |
| Sep 19, 2019 at 18:57 | history | edited | Doc Brown | CC BY-SA 4.0 |
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| Sep 19, 2019 at 18:50 | history | answered | Doc Brown | CC BY-SA 4.0 |