Hi Sebastian As you got correctly i was talking about 4.4.1-rt5 and not 4.1 i replied to by accident. Am Freitag, 12. Februar 2016, 10:07:59 schrieb Sebastian Andrzej Siewior: > On 02/12/2016 09:28 AM, Tim Sander wrote: > > Hi Sebastian > > Hi Tim, > > > Am Sonntag, 16. August 2015, 15:56:30 schrieb Sebastian Andrzej Siewior: > >> I'm pleased to announce the v4.1.5-rt5 patch set. > > > > I have just tested it with a Altera SoC ARM v7. The latencies seem to have > > gotten a little bit worse with each release. The first core has always > > been > > worse (presumably due to interrupt load) but now it dropped to 111µs (rt5) > > from 76µs(rt3) and 54µs(rt2). > > in -rt2 we had bug in migrate disable code which means each task was > running on CPU0. This got partly fixed in -rt3. In -rt3 the scheduler > could assign a task to CPU1 but the task should stay there for ever. > This little detail was fixed in -rt5. > This is one thing that comes to mind. > Lazy-preempt should have been fixed in -rt3, too. This should not give > you higher latencies but higher throughput. > > What about rt4? It is only the stable update so you should see here the > numbers from rt3. If that is true and your numbers are stable it should > be easy to run git bisect between rt4 and rt5. And looking at > https://git.kernel.org/rt/linux-rt-devel/h/v4.4.1-rt5 > the only non-cosmetic change in -rt5 that should affect you is the > migrate-disable fixup from Mike. Ok, each run takes a couple of hours so bisecting should take quite some time but i will give it a try. I started a test with 4.4.1-rt4, if the numbers are within the 70µs ballpark bisecting seems the way to go. If the numbers are higher i suspect that stable update might have a play here. But we will see. Best regards Tim -- 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
