hi, In OS as well RTOS in preemptive environ, the preemption is a policy decided by scheduler which is invoked by timer handler so this interrupts I.E is timer0 interrupts are involved in preemption, normally the context switch is at hardware level so it takes time,what i remember that in RTlinux, the timer is set to interrupt on terminal count mode to give sharp timer resolution unlike in linux in which one cant get very small resolution or alteast they create a overhead,and context switches do not invole any hardware rather software context switch are performed and scheduling policoes depends on the nature of RT processes so right from EDF,Rate monotonic,both are preemptive to FIFO policy also used Prasanna --- jmc@alumni.csie.ncu.edu.tw wrote: > Hi there, > I got a question about RTOS. > In a preemptive priority scheduling OS, how does a > higer priority process preempts the lower one? > Generally, OS will have to do the context switch. My > question is that, does the preemption have OS > interrupt involved (OS generates an interrupt to > signal the context switch)?? If not, how the > preemption is triggered? > > Regards > Ming-Chia > > --------------------------------------------------------- > To Subscribe : > http://www.anart.no/sympa/subrequest/alge > To UnSubscribe: > http://www.anart.no/sympa/sigrequest/alge > __________________________________ Do you Yahoo!? Yahoo! Mail - 50x more storage than other providers! http://promotions.yahoo.com/new_mail -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
