From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752282AbdLATlC (ORCPT ); Fri, 1 Dec 2017 14:41:02 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41244 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751407AbdLATgz (ORCPT ); Fri, 1 Dec 2017 14:36:55 -0500 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 08/17] rcu: Add tracing to irq/NMI dyntick-idle transitions Date: Fri, 1 Dec 2017 11:36:39 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20171201193625.GA20681@linux.vnet.ibm.com> References: <20171201193625.GA20681@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17120119-2213-0000-0000-000002443F2D X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008137; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000243; SDB=6.00953995; UDB=6.00482082; IPR=6.00734069; BA=6.00005726; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00018295; XFM=3.00000015; UTC=2017-12-01 19:36:53 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17120119-2214-0000-0000-00005852446B Message-Id: <1512157008-22355-8-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-12-01_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712010228 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Paul E. McKenney --- include/trace/events/rcu.h | 14 ++++++++------ kernel/rcu/tree.c | 6 ++++++ 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 59d40c454aa0..4674b21247f7 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -421,16 +421,18 @@ TRACE_EVENT(rcu_fqs, /* * Tracepoint for dyntick-idle entry/exit events. These take a string - * as argument: "Start" for entering dyntick-idle mode, "End" for - * leaving it, "--=" for events moving towards idle, and "++=" for events - * moving away from idle. "Error on entry: not idle task" and "Error on - * exit: not idle task" indicate that a non-idle task is erroneously + * as argument: "Start" for entering dyntick-idle mode, "Startirq" for + * entering it from irq/NMI, "End" for leaving it, "Endirq" for leaving it + * to irq/NMI, "--=" for events moving towards idle, and "++=" for events + * moving away from idle. "Error on entry: not idle task" and "Error + * on exit: not idle task" indicate that a non-idle task is erroneously * toying with the idle loop. * * These events also take a pair of numbers, which indicate the nesting * depth before and after the event of interest. Note that task-related - * events use the upper bits of each number, while interrupt-related - * events use the lower bits. + * and interrupt-related events use two separate counters, and that the + * "++=" and "--=" events for irq/NMI will change the counter by two, + * otherwise by one. */ TRACE_EVENT(rcu_dyntick, diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 444aa2b3f24d..d069ba2d8412 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -880,12 +880,15 @@ void rcu_nmi_exit(void) * leave it in non-RCU-idle state. */ if (rdtp->dynticks_nmi_nesting != 1) { + trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, + rdtp->dynticks_nmi_nesting - 2); WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */ rdtp->dynticks_nmi_nesting - 2); return; } /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ + trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0); WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ rcu_dynticks_eqs_enter(); } @@ -1057,6 +1060,9 @@ void rcu_nmi_enter(void) rcu_dynticks_eqs_exit(); incby = 1; } + trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="), + rdtp->dynticks_nmi_nesting, + rdtp->dynticks_nmi_nesting + incby); WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */ rdtp->dynticks_nmi_nesting + incby); barrier(); -- 2.5.2