Re: [PATCH tip/core/rcu 14/15] rcu: Use for_each_rcu_flavor() in TREE_RCU tracing

[Josh Triplett <josh@joshtriplett.org>]

On Fri, Jun 15, 2012 at 05:56:05PM -0700, Paul E. McKenney wrote:
> On Fri, Jun 15, 2012 at 04:59:57PM -0700, Josh Triplett wrote:
> > On Fri, Jun 15, 2012 at 02:06:09PM -0700, Paul E. McKenney wrote:
> > > @@ -129,24 +125,16 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
> > >  		   rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
> > >  }
> > >  
> > > -#define PRINT_RCU_DATA(name, func, m) \
> > > -	do { \
> > > -		int _p_r_d_i; \
> > > -		\
> > > -		for_each_possible_cpu(_p_r_d_i) \
> > > -			func(m, &per_cpu(name, _p_r_d_i)); \
> > > -	} while (0)
> > > -
> > >  static int show_rcudata(struct seq_file *m, void *unused)
> > >  {
> > > -#ifdef CONFIG_TREE_PREEMPT_RCU
> > > -	seq_puts(m, "rcu_preempt:\n");
> > > -	PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data, m);
> > > -#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
> > > -	seq_puts(m, "rcu_sched:\n");
> > > -	PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
> > > -	seq_puts(m, "rcu_bh:\n");
> > > -	PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
> > > +	int cpu;
> > > +	struct rcu_state *rsp;
> > > +
> > > +	for_each_rcu_flavor(rsp) {
> > > +		seq_printf(m, "%s:\n", rsp->name);
> > > +		for_each_possible_cpu(cpu)
> > > +		print_one_rcu_data(m, per_cpu_ptr(rsp->rda, cpu));
> > > +	}
> > 
> > As above, I'd suggest inlining print_one_rcu_data.
> 
> Not this one, too bulky.

I looked at the implementation; it just consists of a pile of calls to
seq_printf.  What about that makes it too bulky to include in the body
of the loop?

> > > @@ -200,6 +188,9 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
> > >  
> > >  static int show_rcudata_csv(struct seq_file *m, void *unused)
> > >  {
> > > +	int cpu;
> > > +	struct rcu_state *rsp;
> > > +
> > >  	seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pgp\",\"pq\",");
> > >  	seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
> > >  	seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\"");
> > > @@ -207,14 +198,11 @@ static int show_rcudata_csv(struct seq_file *m, void *unused)
> > >  	seq_puts(m, "\"kt\",\"ktl\"");
> > >  #endif /* #ifdef CONFIG_RCU_BOOST */
> > >  	seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
> > > -#ifdef CONFIG_TREE_PREEMPT_RCU
> > > -	seq_puts(m, "\"rcu_preempt:\"\n");
> > > -	PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
> > > -#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
> > > -	seq_puts(m, "\"rcu_sched:\"\n");
> > > -	PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
> > > -	seq_puts(m, "\"rcu_bh:\"\n");
> > > -	PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
> > > +	for_each_rcu_flavor(rsp) {
> > > +		seq_printf(m, "\"%s:\"\n", rsp->name);
> > > +		for_each_possible_cpu(cpu)
> > > +			print_one_rcu_data_csv(m, per_cpu_ptr(rsp->rda, cpu));
> > > +	}
> > 
> > As above, I'd suggest inlining print_one_rcu_data_csv.
> 
> Also too bulky.

Also just a few calls to seq_printf. :)

> > > @@ -304,9 +292,9 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
> > >  	struct rcu_node *rnp;
> > >  
> > >  	gpnum = rsp->gpnum;
> > > -	seq_printf(m, "c=%lu g=%lu s=%d jfq=%ld j=%x "
> > > +	seq_printf(m, "%s: c=%lu g=%lu s=%d jfq=%ld j=%x "
> > >  		      "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
> > > -		   rsp->completed, gpnum, rsp->fqs_state,
> > > +		   rsp->name, rsp->completed, gpnum, rsp->fqs_state,
> > >  		   (long)(rsp->jiffies_force_qs - jiffies),
> > >  		   (int)(jiffies & 0xffff),
> > >  		   rsp->n_force_qs, rsp->n_force_qs_ngp,
> > > @@ -329,14 +317,10 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
> > >  
> > >  static int show_rcuhier(struct seq_file *m, void *unused)
> > >  {
> > > -#ifdef CONFIG_TREE_PREEMPT_RCU
> > > -	seq_puts(m, "rcu_preempt:\n");
> > > -	print_one_rcu_state(m, &rcu_preempt_state);
> > > -#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
> > > -	seq_puts(m, "rcu_sched:\n");
> > > -	print_one_rcu_state(m, &rcu_sched_state);
> > > -	seq_puts(m, "rcu_bh:\n");
> > > -	print_one_rcu_state(m, &rcu_bh_state);
> > > +	struct rcu_state *rsp;
> > > +
> > > +	for_each_rcu_flavor(rsp)
> > > +		print_one_rcu_state(m, rsp);
> > 
> > As above, I'd suggest inlining print_one_rcu_state.
> 
> Also too bulky.

This one I'll grant, since it would introduce an additional level of
nested loop.

> > > @@ -377,11 +361,10 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
> > >  
> > >  static int show_rcugp(struct seq_file *m, void *unused)
> > >  {
> > > -#ifdef CONFIG_TREE_PREEMPT_RCU
> > > -	show_one_rcugp(m, &rcu_preempt_state);
> > > -#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
> > > -	show_one_rcugp(m, &rcu_sched_state);
> > > -	show_one_rcugp(m, &rcu_bh_state);
> > > +	struct rcu_state *rsp;
> > > +
> > > +	for_each_rcu_flavor(rsp)
> > > +		show_one_rcugp(m, rsp);
> > 
> > As above, I'd suggest inlining show_one_rcugp.
> 
> Also too bulky.

show_one_rcugp seems like an extremely simple function; what makes it
unsuitable for the body of this loop?

- Josh Triplett