From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751339AbdARErr (ORCPT ); Tue, 17 Jan 2017 23:47:47 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49459 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751184AbdARErq (ORCPT ); Tue, 17 Jan 2017 23:47:46 -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, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH v2 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter Date: Tue, 17 Jan 2017 18:53:56 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170118025316.GB2042@linux.vnet.ibm.com> References: <20170118025316.GB2042@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17011802-0004-0000-0000-00001151E505 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006453; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000199; SDB=6.00809120; UDB=6.00394134; IPR=6.00586477; BA=6.00005066; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013954; XFM=3.00000011; UTC=2017-01-18 02:54:07 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17011802-0005-0000-0000-00007C42BFCD Message-Id: <1484708037-2523-17-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-01-17_17:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1701180043 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Expedited grace periods no longer fall back to normal grace periods in response to lock contention, given that expedited grace periods now use the rcu_node tree so as to avoid contention. This commit therfore removes the expedited_normal counter. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/trace.txt | 5 +---- kernel/rcu/tree.h | 1 - kernel/rcu/tree_trace.c | 3 +-- 3 files changed, 2 insertions(+), 7 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 00a3a38b375a..6549012033f9 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -237,7 +237,7 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of The output of "cat rcu/rcu_preempt/rcuexp" looks as follows: -s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872 +s=21872 wd1=0 wd2=0 wd3=5 enq=0 sc=21872 These fields are as follows: @@ -249,9 +249,6 @@ o "wd1", "wd2", and "wd3" are the number of times that an attempt completed an expedited grace period that satisfies the attempted request. "Our work is done." -o "n" is number of times that a concurrent CPU-hotplug operation - forced a fallback to a normal grace period. - o "enq" is the number of quiescent states still outstanding. o "sc" is the number of times that the attempt to start a diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index fe98dd24adf8..8f750dffb0dd 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -521,7 +521,6 @@ struct rcu_state { struct mutex exp_mutex; /* Serialize expedited GP. */ struct mutex exp_wake_mutex; /* Serialize wakeup. */ unsigned long expedited_sequence; /* Take a ticket. */ - atomic_long_t expedited_normal; /* # fallbacks to normal. */ atomic_t expedited_need_qs; /* # CPUs left to check in. */ struct swait_queue_head expedited_wq; /* Wait for check-ins. */ int ncpus_snap; /* # CPUs seen last time. */ diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c index b1f28972872c..2e932cd1da31 100644 --- a/kernel/rcu/tree_trace.c +++ b/kernel/rcu/tree_trace.c @@ -194,9 +194,8 @@ static int show_rcuexp(struct seq_file *m, void *v) s2 += atomic_long_read(&rdp->exp_workdone2); s3 += atomic_long_read(&rdp->exp_workdone3); } - seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n", + seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu enq=%d sc=%lu\n", rsp->expedited_sequence, s0, s1, s2, s3, - atomic_long_read(&rsp->expedited_normal), atomic_read(&rsp->expedited_need_qs), rsp->expedited_sequence / 2); return 0; -- 2.5.2