CODEWITHSUNDEEP
processoperating-systemswitching
Amol Sharma
Amol Sharma

Reputation: 1591

Context Switch TIme

Does context switch between process take equal time for all the Process ( Constant Time ) or the context switch time is dependent on various local factors which varies from process to process ( like process size,stack size etc..) ?

EDIT : Assume the OS and Hardware are fixed, means will the time be same in a given OS and hwd. environment ?

Upvotes: 2

Views: 1318

Answers (1)

Martin James
Martin James

Reputation: 24907

It varies with hardware as well as OS/process :( To run a thread from a different process, memory-management context, floating-point context etc. must be swapped. This is easier/quicker on some hardware than others.

Drivers vary widely in the time they take to handle their hardware and signal the OS that a thread should be made running - so that's another complication.

In some cases, such a swap may need the preemption of a thread running on another core than the one that received the hardware/software interrupt that initiated the swap. This takes a lot longer than swapping context on the same processor.

It's difficult to come up with any sort of average figure on this. Where would you time it from - the driver interrupt that initiated the inter-process thread swap or from the entry to the scheduler from the driver?

So, overall, we can probably agree that it takes some time and it can vary.

Upvotes: 1

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