On Thu, Aug 19, 2010 at 9:06 AM, Sven-Thorsten Dietrich <thebigcorporation@xxxxxxxxx> wrote: > 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 > > > I see many tracing options. Any trace config in particular? -- Thanks, Manik -- 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
