On Mon, 2009-01-19 at 13:55 -0500, Chris Mason wrote: > I wasn't actually looking at the cost of the checks, even though they do > look higher (if they are using CONFIG_CPUMASK_OFFSTACK anyway). > > The 2.6.24 code would trigger a rescheduling interrupt only when the > prio of the inbound task was higher than the running task. > > This workload has a large number of equal priority rt tasks that are not > bound to a single CPU, and so I think it should trigger more > preempts/reschedules with the today's check_preempt_equal_prio(). Ah yeah. This is one of the things that shows RT being more "responsive" but less on performance. An RT task wants to run ASAP even if that means there's a chance of more interrupts and higher cache misses. The old way would be much faster in general through put, but I measured RT tasks taking up to tens of milliseconds to get scheduled. This is unacceptable for an RT task. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
