On 2018-02-20 19:48:06 [+0100], To Tim Sander wrote: > On 2018-01-26 17:01:09 [+0100], Tim Sander wrote: > > Hi Sebastian Hi Tim, > > I just double checked with your 4.14.15-rt12 release. I have not seen > > any throtteling messages? (the double "cut here" line is no copy error of mine, but > > verbatim kernel output) > > > > Here is the dmesg output of a testrun: > > > > BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 56s! > > Showing busy workqueues and worker pools: > > workqueue mm_percpu_wq: flags=0x8 > > pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/256 > > pending: vmstat_update > > I don't see all of this but I don't see the lockdep detector unless I > boot UP. This bothers me little, let me look why… As I just learned (or have been told): RT_RUNTIME_SHARE on SMP disables the RT throttling if a RT thread went mad. This can be undone via /sys/kernel/debug/sched_features. Without throttling, the workqueue code never gets on the CPU and complains that it is stuck. With throttling it wouldn't happen. However throttling kills everything in the RT class which means it won't process threaded interrupts so an UP system remains "dead" (since you can't access via network/serial, most timer won't expires, …). The benefit is limited. 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
