From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95E9BC43381 for ; Thu, 21 Mar 2019 12:10:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FD23218A5 for ; Thu, 21 Mar 2019 12:10:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728206AbfCUMKY (ORCPT ); Thu, 21 Mar 2019 08:10:24 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:37924 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728138AbfCUMKS (ORCPT ); Thu, 21 Mar 2019 08:10:18 -0400 Received: from p200300d06f010d00c8d029af8ffc83b7.dip0.t-ipconnect.de ([2003:d0:6f01:d00:c8d0:29af:8ffc:83b7] helo=somnus.fritz.box) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1h6wWU-00035a-Cg; Thu, 21 Mar 2019 13:10:14 +0100 From: Anna-Maria Gleixner To: linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, fweisbec@gmail.com, peterz@infradead.org, Anna-Maria Gleixner Subject: [PATCH 4/4] trace/timer: Improve timer tracing Date: Thu, 21 Mar 2019 13:09:21 +0100 Message-Id: <20190321120921.16463-5-anna-maria@linutronix.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190321120921.16463-1-anna-maria@linutronix.de> References: <20190321120921.16463-1-anna-maria@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Timers are added to the timer wheel off by one. This is required in case a timer is queued directly before incrementing jiffies to prevent early timer expiry. When reading a timer trace and relying only on the expiry time of the timer in timer_start trace point and on the now in timer_expiry_entry trace point, it seems that the timer fires late. With the current timer_expiry_entry trace point information only now=jiffies is printed but not the value of base->clk. This makes it impossible to draw a conclusion to the index of base->clk and makes it impossible to examine timer problems without additional trace points. Therefore add the base->clk value to the timer_expire_entry trace point, to be able to calculate the index the timer base is located at during collecting expired timers. Signed-off-by: Anna-Maria Gleixner --- include/trace/events/timer.h | 11 +++++++---- kernel/time/timer.c | 17 +++++++++++++---- 2 files changed, 20 insertions(+), 8 deletions(-) diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h index da975d69c453..dade735657ef 100644 --- a/include/trace/events/timer.h +++ b/include/trace/events/timer.h @@ -89,24 +89,27 @@ TRACE_EVENT(timer_start, */ TRACE_EVENT(timer_expire_entry, - TP_PROTO(struct timer_list *timer), + TP_PROTO(struct timer_list *timer, unsigned long baseclk), - TP_ARGS(timer), + TP_ARGS(timer, baseclk), TP_STRUCT__entry( __field( void *, timer ) __field( unsigned long, now ) __field( void *, function) + __field( unsigned long, baseclk ) ), TP_fast_assign( __entry->timer = timer; __entry->now = jiffies; __entry->function = timer->function; + __entry->baseclk = baseclk; ), - TP_printk("timer=%p function=%ps now=%lu", - __entry->timer, __entry->function, __entry->now) + TP_printk("timer=%p function=%ps now=%lu base->clk=%lu", + __entry->timer, __entry->function, __entry->now, + __entry->baseclk) ); /** diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 8d7918ae4d0c..c0233c1a4ccb 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1293,7 +1293,8 @@ int del_timer_sync(struct timer_list *timer) EXPORT_SYMBOL(del_timer_sync); #endif -static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list *)) +static void call_timer_fn(unsigned long baseclk, struct timer_list *timer, + void (*fn)(struct timer_list *)) { int count = preempt_count(); @@ -1316,7 +1317,7 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list */ lock_map_acquire(&lockdep_map); - trace_timer_expire_entry(timer); + trace_timer_expire_entry(timer, baseclk); fn(timer); trace_timer_expire_exit(timer); @@ -1337,6 +1338,14 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list static void expire_timers(struct timer_base *base, struct hlist_head *head) { + /* + * this value is required for tracing only + * + * base->clk was incremented directly before expire_timers was + * called. But expiry is related to the old base->clk value. + */ + unsigned long baseclk = base->clk - 1; + while (!hlist_empty(head)) { struct timer_list *timer; void (*fn)(struct timer_list *); @@ -1350,11 +1359,11 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head) if (timer->flags & TIMER_IRQSAFE) { raw_spin_unlock(&base->lock); - call_timer_fn(timer, fn); + call_timer_fn(baseclk, timer, fn); raw_spin_lock(&base->lock); } else { raw_spin_unlock_irq(&base->lock); - call_timer_fn(timer, fn); + call_timer_fn(baseclk, timer, fn); raw_spin_lock_irq(&base->lock); } } -- 2.20.1