Hi Ketan, The kernel is not preemptive is kernel mode ..which means a context switch cannot happen if the process is executing in the kernel mode. Say it is executing a system call and it is executing in kernel mode ..Now a timer interrupt occurs and it gets executed in the current process context . The timer interrupt found decrements the process counter ..finds it to be zero and sets the reshed_flag = 1; I want to know when will the context switch happen immediately or when the process will return to user mode ? I guess it wont happen immediately as it is non-preemptive. Thank, Rahul. -----Original Message----- From: Patwardhan, Aniruddha [mailto:Aniruddha_Patwardhan@bmc.com] Sent: Monday, October 21, 2002 12:06 PM To: Sonawane, Rahul (Rahul) Cc: kernelnewbies@nl.linux.org Subject: RE: Linux Scheduler Interrupt handling as explained in Bach will illustrate this in more details, with diagram -Aniruddha -----Original Message----- From: Ketan Mukadam [mailto:kmukadam@neomagic.com] Sent: Monday, October 21, 2002 11:47 AM To: Sonawane, Rahul (Rahul) Cc: kernelnewbies@nl.linux.org Subject: Re: Linux Scheduler The timer interrupt service routine will get executed in the current process context. Kernel non-preemptibility does not include interrupts. Regds Ketan Sonawane, Rahul (Rahul) wrote: > Hi, > I have some questions on linux scheduling. Linux kernel is non-preemptive in kernel mode ..right. Now it is executing > in the kernel mode and a timer interrupt occurs ,Does is preempt ..I mean the timer interrupt is of utmost priority it has > to get processed. Please can someone enlighten me about what will happen if the timer interrupt occurs when it is executing > in kernel mode on behalf of some process. > > Thanks in advance, > Rahul > > > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > > -- "Only the paranoid survives." --- Andy Grove -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
