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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, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 06/14] rcu: Add jiffies-since-GP-activity to show_rcu_gp_kthreads() Date: Sun, 11 Nov 2018 11:28:56 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181111192839.GA32144@linux.ibm.com> References: <20181111192839.GA32144@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18111119-0064-0000-0000-000003722DFC X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010028; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01116014; UDB=6.00577118; IPR=6.00896115; MB=3.00024114; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-11 19:29:10 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111119-0065-0000-0000-00003B4D3C23 Message-Id: <20181111192904.3199-6-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-11_13:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1811110185 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit adds a printout of the number of jiffies since the last time that the RCU grace-period kthread did any processing. This can be useful when tracking down forward-progress issues. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index ea78532183ac..e7c9848d1e1b 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -515,12 +515,14 @@ static const char *gp_state_getname(short gs) void show_rcu_gp_kthreads(void) { int cpu; + unsigned long j; struct rcu_data *rdp; struct rcu_node *rnp; - pr_info("%s: wait state: %s(%d) ->state: %#lx\n", rcu_state.name, - gp_state_getname(rcu_state.gp_state), rcu_state.gp_state, - rcu_state.gp_kthread->state); + j = jiffies - READ_ONCE(rcu_state.gp_activity); + pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %ld\n", + rcu_state.name, gp_state_getname(rcu_state.gp_state), + rcu_state.gp_state, rcu_state.gp_kthread->state, j); rcu_for_each_node_breadth_first(rnp) { if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed)) continue; -- 2.17.1