From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755262Ab3KFQhJ (ORCPT ); Wed, 6 Nov 2013 11:37:09 -0500 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.225]:20760 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750739Ab3KFQhH (ORCPT ); Wed, 6 Nov 2013 11:37:07 -0500 Date: Wed, 6 Nov 2013 11:37:04 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: Yuanhan Liu , mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org, Fengguang Wu , Huang Ying , lkp@linux.intel.com Subject: Re: [PATCH] ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED Message-ID: <20131106113704.41b6ed5c@gandalf.local.home> In-Reply-To: <20130927152908.GE15690@laptop.programming.kicks-ass.net> References: <20130927091427.GE24743@yliu-dev.sh.intel.com> <20130927152908.GE15690@laptop.programming.kicks-ass.net> X-Mailer: Claws Mail 3.9.2 (GTK+ 2.24.20; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.118:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 27 Sep 2013 17:29:08 +0200 Peter Zijlstra wrote: > Subject: ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED > From: Peter Zijlstra > 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 > Signed-off-by: Peter Zijlstra > --- > 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' :