Messages in this thread | | | Date | Wed, 6 Nov 2013 11:37:04 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED |
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On Fri, 27 Sep 2013 17:29:08 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> Subject: ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED > From: Peter Zijlstra <peterz@infradead.org> > Date: Fri Sep 27 17:11:00 CEST 2013 > > Since we now have two need_resched states; trace the two so we can > observe discrepancies.
I see this is dependent on the addition of tif_need_resched() and friends.
> > Cc: Steven Rostedt <rostedt@goodmis.org> > Signed-off-by: Peter Zijlstra <peterz@infradead.org> > --- > kernel/trace/trace.c | 3 ++- > kernel/trace/trace.h | 1 + > kernel/trace/trace_output.c | 13 +++++++++++-- > 3 files changed, 14 insertions(+), 3 deletions(-) > > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -1509,7 +1509,8 @@ tracing_generic_entry_update(struct trac > #endif > ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) | > ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) | > - (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0); > + (tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) | > + (test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0); > } > EXPORT_SYMBOL_GPL(tracing_generic_entry_update); > > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -124,6 +124,7 @@ enum trace_flag_type { > TRACE_FLAG_NEED_RESCHED = 0x04, > TRACE_FLAG_HARDIRQ = 0x08, > TRACE_FLAG_SOFTIRQ = 0x10, > + TRACE_FLAG_PREEMPT_RESCHED = 0x20, > }; > > #define TRACE_BUF_SIZE 1024 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -618,8 +618,17 @@ int trace_print_lat_fmt(struct trace_seq > (entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' : > (entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' : > '.'; > - need_resched = > - (entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'; > + > + if ((entry->flags & TRACE_FLAG_NEED_RESCHED) && > + (entry->flags & TRACE_FLAG_PREEMPT_RESCHED)) > + need_resched = 'N'; > + else if (entry->flags & TRACE_FLAG_NEED_RESCHED) > + need_resched = 'n'; > + else if (entry->flags & TRACE_FLAG_PREEMPT_RESCHED) > + need_resched = 'p'; > + else > + need_resched = '.';
Perhaps we should make this a switch statement?
switch (entry->flags & (TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED)) { case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED: need_resched = 'N'; break; case TRACE_FLAG_NEED_RESCHED: need_resched = 'n'; break; case TRACE_FLAG_PREEMPT_RESCHED: need_resched = 'p'; break; default: need_resched = '.'; break; }
Simply because I find switch statements easier to read than else if statements.
-- Steve
> + > hardsoft_irq = > (hardirq && softirq) ? 'H' : > hardirq ? 'h' :
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