* Thomas Gleixner | 2015-08-04 14:05:10 [+0200]: >On Tue, 4 Aug 2015, Nicholas Mc Guire wrote: >> <snip> >> 3 root -2 0 0 0 0 R 60.3 0.0 5756:16 ksoftirqd/0 >> 23 root -2 0 0 0 0 R 50.8 0.0 4948:08 ksoftirqd/2 >> 17 root -2 0 0 0 0 S 50.6 0.0 4897:13 ksoftirqd/1 >> 29 root -2 0 0 0 0 S 50.4 0.0 4953:24 ksoftirqd/3 > >So ksoftirqd eats 50+% CPU on each core. On an idle system!?! Any >chance that you can get a function trace snapshot out of it? This might be a .config thing, device driver or user land behaviour. Usually ksoftirqd should remain (almost) idle because most of BH work remains in task-context and not in ksoftirqd. tasklets for instance should run in ksoftirqd. So a function trace or event tracing to figure out what is scheduling the softirq might give a pointer. I have here a AMD box with 3 root -2 0 0 0 0 S 1.3 0.0 126:16.31 ksoftirqd/0 18 root -2 0 0 0 0 S 1.3 0.0 136:55.85 ksoftirqd/1 30 root -2 0 0 0 0 S 1.3 0.0 138:50.52 ksoftirqd/3 24 root -2 0 0 0 0 S 1.0 0.0 143:54.28 ksoftirqd/2 with a 15 days uptime. That one percent CPU usage on a idle system looks odd here, too. >Thanks, > > tglx Sebastian -- 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
