@Prabagaran Execution of an instruction, by the CPU, is an ATOMIC operation. Interrupts, if any, will be processed after the execution of the current instruction.
CPU has interrupt pins attached to it. Whenever an interrupt occurs, the CPU will be informed about the interrupt through these hardwired pins. That's how the CPU will get to know the occurrence of an interrupt. For now, please assume that somehow, these pins will be set to the corresponding values, if any interrupt occurs. Please refer to the Intel's Manual for further details on Interrupt Handling. Now, when a timer interrupt occurs, the kernel will get to know that the time quantum assigned to the current process has expired and then it loads the next waiting process to execute on the CPU. Hope this helps. -- CM Saikanth Varma On Sun, May 2, 2010 at 10:25 PM, praba garan <prabagara...@gmail.com> wrote: > @ Pradeep > > *CPU stop its current processing and goes to the interrupt subroutine* > > you have mentioned that the CPU stops its current processing and goes to > the interrupt subroutine.. > > My Question is how does the CPU stops its execution(any special hardware > involved) because it is busy in executing the current instruction. > > > With Regards, > Prabagaran. > > > > On Sun, May 2, 2010 at 4:02 AM, pradeep verma <ppradeep...@gmail.com>wrote: > >> lets suppose Processor executing a instruction(process1) and another >> process2 tries to take the control of CPU so inorder to inform CPU it has to >> interrupt the CPU right >> now we know that if interrupt comes CPU stop its current processing and >> goes to the interrupt subroutine...now CPU knows that its a pre-emption >> interrupt so CPU first run its short term scheduler(this will inform CPU >> that the interruting process priority is less or greater ..n if greater than >> CPU goes to previous process1 preempt it and start executing higher priority >> process2 ) >> >> I think its clear >> >> Regards >> Pradeep >> >> >> >> On Sun, May 2, 2010 at 3:06 AM, praba garan <prabagara...@gmail.com>wrote: >> >>> @ Guillermo Garcia >>> >>> The link gives the overall abstract idea. >>> I am talking in register level. >>> When a user process executes >>> >>> 1. PC program counter will contain the address of the next instruction in >>> user code. >>> 2. Processor registers(accumulator ...) contain the current instruction >>> data. >>> >>> Then where does the interrupt actually arrives?? >>> >>> And by that time the user process the control, then who does the >>> preempting and how?? >>> >>> With Regards, >>> Prabagaran. >>> >>> >>> >>> On Sun, May 2, 2010 at 2:35 AM, Guillermo Garcia >>> <gegarci...@gmail.com>wrote: >>> >>>> >>>> read here -> http://en.wikipedia.org/wiki/Preemption_%28computing%29 >>>> >>>> >>>> >>>> Time slice >>>> >>>> The period of time for which a process is allowed to run in a preemptive >>>> multitasking system is generally called the *time slice*, or *quantum*. >>>> The scheduler is run once every time slice to choose the next process to >>>> run. If the time slice is too short then the scheduler will consume too >>>> much >>>> processing time. >>>> >>>> An interrupt <http://en.wikipedia.org/wiki/Interrupt> is scheduled to >>>> allow the operating system<http://en.wikipedia.org/wiki/Operating_system> >>>> kernel <http://en.wikipedia.org/wiki/Kernel_%28computer_science%29> to >>>> switch between processes when their time slices expire, effectively >>>> allowing >>>> the processor’s time to be shared between a number of tasks, giving the >>>> illusion that it is dealing with these tasks simultaneously, or >>>> concurrently. The operating system which controls such a design is called a >>>> multi-tasking system. >>>> >>>> >>>> >>>> >>>> On Sat, May 1, 2010 at 5:26 PM, praba garan <prabagara...@gmail.com>wrote: >>>> >>>>> @ Guillermo Garcia >>>>> >>>>> Suppose a user program is executing and and clock interrupt arrives.. >>>>> Then who receives the interrupt?? >>>>> Can you xplain me the clock interrupt(like any hardwares involved) bit >>>>> detailed?? >>>>> >>>>> With Regards, >>>>> Prabagaran. >>>>> >>>>> >>>>> >>>>> On Sun, May 2, 2010 at 1:38 AM, Guillermo Garcia <gegarci...@gmail.com >>>>> > wrote: >>>>> >>>>>> The scheduler takes control with a clock interruption. Then it >>>>>> analyzes if it has to preempt or not the running task. >>>>>> >>>>>> On Sat, May 1, 2010 at 5:00 PM, praba garan >>>>>> <prabagara...@gmail.com>wrote: >>>>>> >>>>>>> Hi all, >>>>>>> I have a doubt in OS. >>>>>>> The scheduler does the process of preemption. >>>>>>> And one processor can run atmost 1 instruction at a time. >>>>>>> Then how & where does the scheduler run?? >>>>>>> >>>>>>> With Regards, >>>>>>> Prabagaran. >>>>>>> >>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "Algorithm Geeks" group. >>>>>>> To post to this group, send email to algoge...@googlegroups.com. >>>>>>> To unsubscribe from this group, send email to >>>>>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>>>>> . >>>>>>> For more options, visit this group at >>>>>>> http://groups.google.com/group/algogeeks?hl=en. >>>>>>> >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "Algorithm Geeks" group. >>>>>> To post to this group, send email to algoge...@googlegroups.com. >>>>>> To unsubscribe from this group, send email to >>>>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>>>> . >>>>>> For more options, visit this group at >>>>>> http://groups.google.com/group/algogeeks?hl=en. >>>>>> >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Algorithm Geeks" group. >>>>> To post to this group, send email to algoge...@googlegroups.com. >>>>> To unsubscribe from this group, send email to >>>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>>> . >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/algogeeks?hl=en. >>>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Algorithm Geeks" group. >>>> To post to this group, send email to algoge...@googlegroups.com. >>>> To unsubscribe from this group, send email to >>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>> . >>>> For more options, visit this group at >>>> http://groups.google.com/group/algogeeks?hl=en. >>>> >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "Algorithm Geeks" group. >>> To post to this group, send email to algoge...@googlegroups.com. >>> To unsubscribe from this group, send email to >>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>> . >>> For more options, visit this group at >>> http://groups.google.com/group/algogeeks?hl=en. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Algorithm Geeks" group. >> To post to this group, send email to algoge...@googlegroups.com. >> To unsubscribe from this group, send email to >> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >> . >> For more options, visit this group at >> http://groups.google.com/group/algogeeks?hl=en. >> > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to algoge...@googlegroups.com. > To unsubscribe from this group, send email to > algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
