Re: [PATCH 3/3] rcu/trace: Add name of the source for gp_seq to prevent confusion

2020-06-20 Thread Paul E. McKenney 
On Sat, Jun 20, 2020 at 01:36:08AM -0400, Joel Fernandes wrote:
> On Fri, Jun 19, 2020 at 10:40:01AM -0700, Paul E. McKenney wrote:
> > On Thu, Jun 18, 2020 at 10:07:18PM -0400, Joel Fernandes wrote:
> > > On Thu, Jun 18, 2020 at 09:36:41PM -0400, Joel Fernandes (Google) wrote:
> > > [...]
> > > > @@ -2019,7 +2019,7 @@ static int __noreturn rcu_gp_kthread(void *unused)
> > > > cond_resched_tasks_rcu_qs();
> > > > WRITE_ONCE(rcu_state.gp_activity, jiffies);
> > > > WARN_ON(signal_pending(current));
> > > > -   trace_rcu_grace_period(rcu_state.name, 
> > > > rcu_state.gp_seq,
> > > > +   trace_rcu_grace_period(rcu_state.name, 
> > > > TPS("rsp"), rcu_state.gp_seq,
> > > >TPS("reqwaitsig"));
> > > > }
> > > >  
> > > > @@ -2263,7 +2263,7 @@ int rcutree_dying_cpu(unsigned int cpu)
> > > > return 0;
> > > >  
> > > > blkd = !!(rnp->qsmask & rdp->grpmask);
> > > > -   trace_rcu_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq),
> > > > +   trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> > > > READ_ONCE(rnp->gp_seq),
> > > 
> > > This should be: TPS("rnp")  :-(
> > > 
> > > Happy to fix it up and resend if you'd like. Thanks!
> > 
> > I queued and pushed 1/2 and 2/2.
> 
> Thanks!
> 
> > but again, I am still not at all
> > convinced by 3/3.  If you want to make RCU trace output human
> > readable, post-processing will be needed.
> 
> Or I could post-process the code before building it since the pattern seems
> easy to parse ;-)

For this one thing, perhaps.  For most other information of interest,
doing so in-kernel would not be so good, for example, from a
lock-contention viewpoint.

Thanx, Paul

Re: [PATCH 3/3] rcu/trace: Add name of the source for gp_seq to prevent confusion

2020-06-19 Thread Joel Fernandes 
On Fri, Jun 19, 2020 at 10:40:01AM -0700, Paul E. McKenney wrote:
> On Thu, Jun 18, 2020 at 10:07:18PM -0400, Joel Fernandes wrote:
> > On Thu, Jun 18, 2020 at 09:36:41PM -0400, Joel Fernandes (Google) wrote:
> > [...]
> > > @@ -2019,7 +2019,7 @@ static int __noreturn rcu_gp_kthread(void *unused)
> > >   cond_resched_tasks_rcu_qs();
> > >   WRITE_ONCE(rcu_state.gp_activity, jiffies);
> > >   WARN_ON(signal_pending(current));
> > > - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq,
> > > + trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> > > rcu_state.gp_seq,
> > >  TPS("reqwaitsig"));
> > >   }
> > >  
> > > @@ -2263,7 +2263,7 @@ int rcutree_dying_cpu(unsigned int cpu)
> > >   return 0;
> > >  
> > >   blkd = !!(rnp->qsmask & rdp->grpmask);
> > > - trace_rcu_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq),
> > > + trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> > > READ_ONCE(rnp->gp_seq),
> > 
> > This should be: TPS("rnp")  :-(
> > 
> > Happy to fix it up and resend if you'd like. Thanks!
> 
> I queued and pushed 1/2 and 2/2.

Thanks!

> but again, I am still not at all
> convinced by 3/3.  If you want to make RCU trace output human
> readable, post-processing will be needed.

Or I could post-process the code before building it since the pattern seems
easy to parse ;-)

 - Joel

Re: [PATCH 3/3] rcu/trace: Add name of the source for gp_seq to prevent confusion

2020-06-19 Thread Paul E. McKenney 
On Thu, Jun 18, 2020 at 10:07:18PM -0400, Joel Fernandes wrote:
> On Thu, Jun 18, 2020 at 09:36:41PM -0400, Joel Fernandes (Google) wrote:
> [...]
> > @@ -2019,7 +2019,7 @@ static int __noreturn rcu_gp_kthread(void *unused)
> > cond_resched_tasks_rcu_qs();
> > WRITE_ONCE(rcu_state.gp_activity, jiffies);
> > WARN_ON(signal_pending(current));
> > -   trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq,
> > +   trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> > rcu_state.gp_seq,
> >TPS("reqwaitsig"));
> > }
> >  
> > @@ -2263,7 +2263,7 @@ int rcutree_dying_cpu(unsigned int cpu)
> > return 0;
> >  
> > blkd = !!(rnp->qsmask & rdp->grpmask);
> > -   trace_rcu_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq),
> > +   trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> > READ_ONCE(rnp->gp_seq),
> 
> This should be: TPS("rnp")  :-(
> 
> Happy to fix it up and resend if you'd like. Thanks!

I queued and pushed 1/2 and 2/2, but again, I am still not at all
convinced by 3/3.  If you want to make RCU trace output human
readable, post-processing will be needed.

Thanx, Paul

Re: [PATCH 3/3] rcu/trace: Add name of the source for gp_seq to prevent confusion

2020-06-18 Thread Joel Fernandes 
On Thu, Jun 18, 2020 at 09:36:41PM -0400, Joel Fernandes (Google) wrote:
[...]
> @@ -2019,7 +2019,7 @@ static int __noreturn rcu_gp_kthread(void *unused)
>   cond_resched_tasks_rcu_qs();
>   WRITE_ONCE(rcu_state.gp_activity, jiffies);
>   WARN_ON(signal_pending(current));
> - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq,
> + trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> rcu_state.gp_seq,
>  TPS("reqwaitsig"));
>   }
>  
> @@ -2263,7 +2263,7 @@ int rcutree_dying_cpu(unsigned int cpu)
>   return 0;
>  
>   blkd = !!(rnp->qsmask & rdp->grpmask);
> - trace_rcu_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq),
> + trace_rcu_grace_period(rcu_state.name, TPS("rsp"), 
> READ_ONCE(rnp->gp_seq),

This should be: TPS("rnp")  :-(

Happy to fix it up and resend if you'd like. Thanks!