linux-kernel - Re: [PATCH 2/3] tracing: Record task flag NEED_RESCHED

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Message-ID: <20241009133328.23fc671c@gandalf.local.home>
Date: Wed, 9 Oct 2024 13:33:28 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Ankur Arora <ankur.a.arora@...cle.com>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 linux-trace-kernel@...r.kernel.org, linux-kernel@...r.kernel.org, Peter
 Zijlstra <peterz@...radead.org>, tglx@...utronix.de, mingo@...nel.org,
 juri.lelli@...hat.com, vincent.guittot@...aro.org,
 dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
 vschneid@...hat.com, efault@....de, Masami Hiramatsu <mhiramat@...nel.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH 2/3] tracing: Record task flag NEED_RESCHED_LAZY.

On Wed, 09 Oct 2024 10:30:28 -0700
Ankur Arora <ankur.a.arora@...cle.com> wrote:

> > +++ b/kernel/trace/trace.c
> > @@ -2544,6 +2544,8 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status)
> >  		trace_flags |= TRACE_FLAG_NEED_RESCHED;
> >  	if (test_preempt_need_resched())
> >  		trace_flags |= TRACE_FLAG_PREEMPT_RESCHED;
> > +	if (tif_test_bit(TIF_NEED_RESCHED_LAZY))  
> 
> TIF_NEED_RESCHED_LAZY falls back to TIF_NEED_RESCHED without
> CONFIG_ARCH_HAS_PREEMPT_LAZY. So, you might need to add an explicit
> check for that as well.
> 
> With that,
>  Reviewed-by: Ankur Arora <ankur.a.arora@...cle.com>
> 
> Ankur
> 

So this should be:

	if (IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY) &&
	    tif_test_bit(TIF_NEED_RESCHED_LAZY))

?

-- Steve


> > +		trace_flags |= TRACE_FLAG_NEED_RESCHED_LAZY;
> >  	return (trace_flags << 16) | (min_t(unsigned int, pc & 0xff, 0xf)) |
> >  		(min_t(unsigned int, migration_disable_value(), 0xf)) << 4;
> >  }
> > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> > index 829daa0764dd9..23ca2155306b1 100644
> > --- a/kernel/trace/trace_output.c
> > +++ b/kernel/trace/trace_output.c
> > @@ -463,17 +463,29 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
> >  		!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_SUPPORT) ? 'X' :
> >  		'.';
> >
> > -	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED |
> > +	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_NEED_RESCHED_LAZY |
> >  				TRACE_FLAG_PREEMPT_RESCHED)) {
> > +	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_NEED_RESCHED_LAZY | TRACE_FLAG_PREEMPT_RESCHED:
> > +		need_resched = 'B';
> > +		break;
> >  	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED:
> >  		need_resched = 'N';
> >  		break;
> > +	case TRACE_FLAG_NEED_RESCHED_LAZY | TRACE_FLAG_PREEMPT_RESCHED:
> > +		need_resched = 'L';
> > +		break;
> > +	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_NEED_RESCHED_LAZY:
> > +		need_resched = 'b';
> > +		break;
> >  	case TRACE_FLAG_NEED_RESCHED:
> >  		need_resched = 'n';
> >  		break;
> >  	case TRACE_FLAG_PREEMPT_RESCHED:
> >  		need_resched = 'p';
> >  		break;
> > +	case TRACE_FLAG_NEED_RESCHED_LAZY:
> > +		need_resched = 'l';
> > +		break;
> >  	default:
> >  		need_resched = '.';
> >  		break;