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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 05/17] rcutorture: Affinity forward-progress test to avoid housekeeping CPUs Date: Sun, 11 Nov 2018 12:20:15 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181111201956.GA11935@linux.ibm.com> References: <20181111201956.GA11935@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18111120-0072-0000-0000-000003C6F5DD X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010028; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01116031; UDB=6.00577118; IPR=6.00896132; MB=3.00024115; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-11 20:20:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111120-0073-0000-0000-00004A13578E Message-Id: <20181111202027.13585-5-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-1811110194 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit affinities the forward-progress tests to avoid hogging a housekeeping CPU on the theory that the offloaded callbacks will be running on those housekeeping CPUs. Signed-off-by: Paul E. McKenney [ paulmck: Fix NULL-pointer issue located by kbuild test robot. ] Tested-by: Rong Chen --- kernel/rcu/rcu.h | 2 ++ kernel/rcu/rcutorture.c | 1 + kernel/rcu/tree_plugin.h | 11 +++++++++++ 3 files changed, 14 insertions(+) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 2866166863f0..0f0f5ae8c3d4 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -539,8 +539,10 @@ extern struct workqueue_struct *rcu_par_gp_wq; #ifdef CONFIG_RCU_NOCB_CPU bool rcu_is_nocb_cpu(int cpu); +void rcu_bind_current_to_nocb(void); #else static inline bool rcu_is_nocb_cpu(int cpu) { return false; } +static inline void rcu_bind_current_to_nocb(void) { } #endif #endif /* __LINUX_RCU_H */ diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index bcc33bb8d9a6..36a3bc42782d 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1803,6 +1803,7 @@ static int rcu_torture_fwd_prog(void *args) int tested_tries = 0; VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started"); + rcu_bind_current_to_nocb(); if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST)) set_user_nice(current, MAX_NICE); do { diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 05915e536336..1db2b0780c62 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2587,6 +2587,17 @@ static bool init_nocb_callback_list(struct rcu_data *rdp) return true; } +/* + * Bind the current task to the offloaded CPUs. If there are no offloaded + * CPUs, leave the task unbound. Splat if the bind attempt fails. + */ +void rcu_bind_current_to_nocb(void) +{ + if (cpumask_available(rcu_nocb_mask) && cpumask_weight(rcu_nocb_mask)) + WARN_ON(sched_setaffinity(current->pid, rcu_nocb_mask)); +} +EXPORT_SYMBOL_GPL(rcu_bind_current_to_nocb); + #else /* #ifdef CONFIG_RCU_NOCB_CPU */ static bool rcu_nocb_cpu_needs_barrier(int cpu) -- 2.17.1