On Thu, 2010-08-19 at 07:59 -0700, Nivedita Singhvi wrote: > On 08/17/2010 03:22 PM, Manikandan Ramachandran wrote: > > > > I see a scenario where higher priority task is ready to run but lower > > priority IRQ thread is hogging the cpu. Please see the timeline log > > below: > > > > GIVE ffff0c1c [Comment: High priority IRQ thread wakes up high > > priority process at jiffy 0xffff0c1c] > > **ffff0c21**##ffff0c21##**ffff0c21**##ffff0c21##**ffff0c21**##ffff0c21##**ffff0c21**##ffff0c21##**ffff0c21**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c22**##ffff0c22##**ffff0c23**##ffff0c23##**ffff0c23**##ffff0c23##**ffff0c23**##ffff0c24##**ffff0c24**##ffff0c24##**ffff0c24**##ffff0c24## > > [Comment: Low priority IDE[ide_intr] handler hogs CPU for almost 3 ms] > > GOTffff0c26 [Comment: High priority task wakes up after 10 ms!!] > > > > I fail to understand why scheduler failed to schedule high priority > > task 10 times in a row. FYI, I have put IDE thread to SCHED_NORMAL > > while high priority thread and task to SCHED_FIFO. > > Not really sure from the above what's going on, what priorities > you are running at, etc. > > You might want look at the output of "ps -eLo pid,rtprio,policy,comm" > to see if you can confirm your scheduler attributes. > Also, use the tracing facilities, as its hard to understand your time line and the source of it. I think if your priorities are right, your kernel config is right, and your measurement tool doesn't interfere, 10 ms latency is incredibly unlikely. > thanks, > Nivedita > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
