On Fri, 2025-02-14 at 09:31 +0100, Florian Paul Schmidt wrote: > Hi again! > > On 1/14/2025 11:28 AM, Mike Galbraith wrote: > > [...] > > > This seems rather odd, one core diddling memory is the worst case. Any > > arm experts out there know why that would be? > > > > pi5, locked at 2.4GHz: > > > > taskset -c 3 stress -m 1 --vm-bytes 1G --vm-stride 16 --vm-keep --timeout 60s;killall cyclictest > > > > T: 0 (23157) P:99 I:1000 C: 63421 Min: 1 Act: 12 Avg: 27 Max: 1378 > > T: 1 (23158) P:99 I:1500 C: 42327 Min: 1 Act: 32 Avg: 29 Max: 1734 > > T: 2 (23159) P:99 I:2000 C: 31744 Min: 1 Act: 18 Avg: 28 Max: 1353 > > T: 3 (23160) P:99 I:2500 C: 25393 Min: 1 Act: 11 Avg: 6 Max: 39 > > > > I wonder if there is still a way to save the day, i.e. use the RPI5 as a > somewhat capable RT-system by > > 1. making sure that the RT load does not do anything nasty - this is > mostly under the users' control since they can setup their RT load to > not do this. I think that's the answer, don't expect miracles from cute/dinky boxen. Beating crap out of any box is only useful for finding limits, has nothing to do with "RT capable". A box is RT capable iff a given RT load's hard constraints can be met on that box. Both of our stress results show only that if you need amazing memory performance, dinky pi5 is not for you :) -Mike
