On Wed, Oct 02, 2024 at 11:01:03AM +0200, Tomas Glozar wrote: > út 1. 10. 2024 v 18:47 odesílatel Paul E. McKenney <paulmck@xxxxxxxxxx> napsal: > > Huh, 50MB and growing. I need to limit the buffer size as well. > > How about "trace_buf_size=2k"? The default is 1,441,792, just > > over 1m. > > > Yeah, limiting the size of the buffer is the way to go, we only need > the last n entries before the oops. > > > Except that I am not getting either dl_server_start() or dl_server_stop(), > > perhaps because they are not being invoked in this short test run. > > So try some function that is definitely getting invoked, such as > > rcu_sched_clock_irq(). > > > > No joy there, either, so maybe add "ftrace=function"? > > > > No: "[ 1.542360] ftrace bootup tracer 'function' not registered." > > > Did you enable CONFIG_BOOTTIME_TRACING and CONFIG_FUNCTION_TRACER? > They are not set in the default configuration for TREE03: > > $ grep -E '(FUNCTION_TRACER)|(BOOTTIME_TRACING)' > ./tools/testing/selftests/rcutorture/res/2024.09.26-14.35.03/TREE03/.config > CONFIG_HAVE_FUNCTION_TRACER=y > # CONFIG_BOOTTIME_TRACING is not set > # CONFIG_FUNCTION_TRACER is not set Ah, thank you! I knew I must be forgetting something. Now a short test gets me things like this: [ 304.572701] torture_-190 13d.h2. 302863957us : rcu_is_cpu_rrupt_from_idle <-rcu_sched_clock_irq > > Especially given that I don't have a QEMU monitor for these 100 runs. > > > > But if there is a way to do this programatically from within the > > kernel, I would be happy to give it a try. > > > > > Also I'd say here we're mostly interested in the sequence of events leading > > > us to the warn (dl_server_start() when the DL entity is somehow still > > > enqueued) rather than the state of things when the warn is hit, and for > > > that dumping the ftrace buffer to the console sounds good enough to me. > > > > That I can do!!! Give or take function tracing appearing not to work > > for me from the kernel command line. :-( > > > > Thanx, Paul > > > > Thanks for trying to get details about the bug. See my comment above > about the config options to enable function tracing. I will check up on last night's run for heisenbug-evaluation purposes, and if it did trigger, restart with this added: --kconfigs "CONFIG_BOOTTIME_TRACING=y CONFIG_FUNCTION_TRACER=y" > FYI I have managed to reproduce the bug on our infrastructure after 21 > hours of 7*TREE03 and I will continue with trying to reproduce it with > the tracers we want. Even better!!! Thanx, Paul
