TEST CASE: I was able to put problem clearly visible using cyclictest, a realtime kernel test utility, on a couple of systems.
[Dynamic Ticks on]
abogani@picasso:~/WIP/rt-tests$ sudo ./cyclictest -t1 -n -p99 -q -l200000
T: 0 ( 7140) P:99 I:1000 C: 200000 Min: 4 Act: 40 Avg: 65 Max: 12047
SRU Justification:
Impact: That bug affect all rt kernel flavour users. From a realtime point of view this is a severe regression.
Fix Description: To prevent this latency we need to disable Dynamic Ticks.
Patch is very simple and safe (one line in rt kernel configuration): kernel. ubuntu. com/git? p=abogani/ ubuntu- hardy-rt. git;a=commit; h=f80aed2d95a5b e145a31b80d30fa d86672b16e8c
http://
Drawback: A bit more power consumption.
TEST CASE: I was able to put problem clearly visible using cyclictest, a realtime kernel test utility, on a couple of systems. picasso: ~/WIP/rt- tests$ sudo ./cyclictest -t1 -n -p99 -q -l200000
[Dynamic Ticks on]
abogani@
T: 0 ( 7140) P:99 I:1000 C: 200000 Min: 4 Act: 40 Avg: 65 Max: 12047
[Dynamic Ticks off] picasso: ~/WIP/rt- tests$ sudo ./cyclictest -t1 -n -p99 -q -l200000
abogani@
T: 0 ( 6481) P:99 I:1000 C: 200000 Min: 2 Act: 6 Avg: 6 Max: 321