Hi Sri, Replying to the list...
On Thu, Sep 9, 2010 at 5:08 PM, Sri Ram Vemulpali wrote: > Hi, > Can any one explain, when interrupt handler schedules softirq, for bottom > half work, when is that softirq is executed. Is it immediately after > interrupt handler context or after some time later when scheduler was > invoked. Softirqs are run with interrupts enabled, and run when all of the nested irqs have completed. Task switching is suspended while irqs/softirs are being run. IRQA occurs IRQA handler gets called IRQB occurs, interrupting IRQA (assuming IRQA was setup to allow itself to be interrupted) IRQB schedules a softirq IRQB exits IRQA continues to run IRQA exits we're now in a situation where the IRQ depth is zero, so softirqs are run. when all softirqs are finished, then regular scheduling of tasks resumes. > I am trying to understand execution context of BHs. I know that tasklets > execute at relaxed time when system deems to execute. But what about > softirq. Since softirq's are in nature high in priority, therefore they > should run immediately after IRQ. I am trying to understand is there any > latency between IRQ and softirq execution scheduled by that corresponding > IRQ. Please can anyone explain the sequence of operations how the softirq is > recognized (that it was set) and scheduled to execute. softirqs and tasklets are really the same thing (as far as I know). They run with interrupts enabled, but preemption disabled. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
