On Wed, 2 Aug 2017 12:02:21 +0530 Pratyush Anand <pan...@redhat.com> wrote:
> Hi Steve, > > I am using a 3.10 based kernel, and when I enable function_graph with one > particular x86_64 machine, I encounter rcu_sched stall. > > echo function_graph > /sys/kernel/debug/tracing/current_tracer > echo 1 > /sys/kernel/debug/tracing/tracing_on > > If I use 4.13-rc2, then its better, but still goes for it after a bit of > stressing with stressng. > > It looks like that this behavior should be expected with a loaded system > (like > that of ftrace-graph tracing for all available function) which can cause RCU > stall warning. But,I am not an expert. So, whats your opinion on it? > > I tried to bisect and there was no particular function which can cause this. > It looked like that when we had more than 5000 functions in > set_ftrace_filter, > we start getting such warnings. Tried by putting some most hit functions > like > spin_lock* etc in set_ftrace_notrace. Still, no help. Do you have some > suggestion for further debugging pointers? > > log with 3.10 based kernel Can you send me the config. I'm also guessing that this is a RHEL 3.10 based kernel (which means it's not 3.10 at all). -- Steve
