From: Waiman Long <longman@redhat.com> To: Alex Kogan <alex.kogan@oracle.com>, linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com, jglauber@marvell.com Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, dave.dice@oracle.com Subject: Re: [PATCH v9 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Date: Thu, 23 Jan 2020 09:15:55 -0500 [thread overview] Message-ID: <d751a8ef-aae8-ca70-6a28-79dd8bee2324@redhat.com> (raw) In-Reply-To: <20200115035920.54451-4-alex.kogan@oracle.com> On 1/14/20 10:59 PM, Alex Kogan wrote: > +static int __init cna_init_nodes(void) > +{ > + unsigned int cpu; > + > + /* > + * this will break on 32bit architectures, so we restrict > + * the use of CNA to 64bit only (see arch/x86/Kconfig) > + */ > + BUILD_BUG_ON(sizeof(struct cna_node) > sizeof(struct qnode)); > + /* we store an ecoded tail word in the node's @locked field */ > + BUILD_BUG_ON(sizeof(u32) > sizeof(unsigned int)); > + > + for_each_possible_cpu(cpu) > + cna_init_nodes_per_cpu(cpu); > + > + return 0; > +} > +early_initcall(cna_init_nodes); > + I just realized that you shouldn't call cna_init_nodes as an early_initcall. Instead, > +/* > + * Switch to the NUMA-friendly slow path for spinlocks when we have > + * multiple NUMA nodes in native environment, unless the user has > + * overridden this default behavior by setting the numa_spinlock flag. > + */ > +void __init cna_configure_spin_lock_slowpath(void) > +{ > + if ((numa_spinlock_flag == 1) || > + (numa_spinlock_flag == 0 && nr_node_ids > 1 && > + pv_ops.lock.queued_spin_lock_slowpath == > + native_queued_spin_lock_slowpath)) { > + pv_ops.lock.queued_spin_lock_slowpath = > + __cna_queued_spin_lock_slowpath; > + > + pr_info("Enabling CNA spinlock\n"); > + } > +} call it when it is sure that CNA spinlock is going to be used. At this point, the system is still in UP mode and the slowpath will not be called. Cheers, Longman
WARNING: multiple messages have this Message-ID (diff)
From: Waiman Long <longman@redhat.com> To: Alex Kogan <alex.kogan@oracle.com>, linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com, jglauber@marvell.com Cc: dave.dice@oracle.com, steven.sistare@oracle.com, daniel.m.jordan@oracle.com Subject: Re: [PATCH v9 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Date: Thu, 23 Jan 2020 09:15:55 -0500 [thread overview] Message-ID: <d751a8ef-aae8-ca70-6a28-79dd8bee2324@redhat.com> (raw) In-Reply-To: <20200115035920.54451-4-alex.kogan@oracle.com> On 1/14/20 10:59 PM, Alex Kogan wrote: > +static int __init cna_init_nodes(void) > +{ > + unsigned int cpu; > + > + /* > + * this will break on 32bit architectures, so we restrict > + * the use of CNA to 64bit only (see arch/x86/Kconfig) > + */ > + BUILD_BUG_ON(sizeof(struct cna_node) > sizeof(struct qnode)); > + /* we store an ecoded tail word in the node's @locked field */ > + BUILD_BUG_ON(sizeof(u32) > sizeof(unsigned int)); > + > + for_each_possible_cpu(cpu) > + cna_init_nodes_per_cpu(cpu); > + > + return 0; > +} > +early_initcall(cna_init_nodes); > + I just realized that you shouldn't call cna_init_nodes as an early_initcall. Instead, > +/* > + * Switch to the NUMA-friendly slow path for spinlocks when we have > + * multiple NUMA nodes in native environment, unless the user has > + * overridden this default behavior by setting the numa_spinlock flag. > + */ > +void __init cna_configure_spin_lock_slowpath(void) > +{ > + if ((numa_spinlock_flag == 1) || > + (numa_spinlock_flag == 0 && nr_node_ids > 1 && > + pv_ops.lock.queued_spin_lock_slowpath == > + native_queued_spin_lock_slowpath)) { > + pv_ops.lock.queued_spin_lock_slowpath = > + __cna_queued_spin_lock_slowpath; > + > + pr_info("Enabling CNA spinlock\n"); > + } > +} call it when it is sure that CNA spinlock is going to be used. At this point, the system is still in UP mode and the slowpath will not be called. Cheers, Longman _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-01-23 14:16 UTC|newest] Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-15 3:59 [PATCH v9 0/5] Add NUMA-awareness to qspinlock Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-15 3:59 ` [PATCH v9 1/5] locking/qspinlock: Rename mcs lock/unlock macros and make them more generic Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-15 3:59 ` [PATCH v9 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-15 3:59 ` [PATCH v9 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-23 9:26 ` Peter Zijlstra 2020-01-23 9:26 ` Peter Zijlstra 2020-01-23 9:26 ` Peter Zijlstra 2020-01-23 10:06 ` Peter Zijlstra 2020-01-23 10:06 ` Peter Zijlstra 2020-01-23 10:06 ` Peter Zijlstra 2020-01-23 10:16 ` Peter Zijlstra 2020-01-23 10:16 ` Peter Zijlstra 2020-01-23 10:16 ` Peter Zijlstra 2020-01-23 11:22 ` Will Deacon 2020-01-23 11:22 ` Will Deacon 2020-01-23 13:17 ` Peter Zijlstra 2020-01-23 13:17 ` Peter Zijlstra 2020-01-23 13:17 ` Peter Zijlstra 2020-01-23 14:15 ` Waiman Long [this message] 2020-01-23 14:15 ` Waiman Long 2020-01-23 15:29 ` Peter Zijlstra 2020-01-23 15:29 ` Peter Zijlstra 2020-01-23 15:29 ` Peter Zijlstra 2020-01-15 3:59 ` [PATCH v9 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-01-23 19:55 ` Waiman Long 2020-01-23 19:55 ` Waiman Long 2020-01-23 20:39 ` Waiman Long 2020-01-23 20:39 ` Waiman Long 2020-01-23 23:39 ` Alex Kogan 2020-01-23 23:39 ` Alex Kogan 2020-01-15 3:59 ` [PATCH v9 5/5] locking/qspinlock: Introduce the shuffle reduction optimization " Alex Kogan 2020-01-15 3:59 ` Alex Kogan 2020-03-02 1:14 ` [locking/qspinlock] 7b6da71157: unixbench.score 8.4% improvement kernel test robot 2020-03-02 1:14 ` kernel test robot 2020-03-02 1:14 ` kernel test robot 2020-01-22 11:45 ` [PATCH v9 0/5] Add NUMA-awareness to qspinlock Lihao Liang 2020-01-22 11:45 ` Lihao Liang 2020-01-22 17:24 ` Waiman Long 2020-01-22 17:24 ` Waiman Long 2020-01-23 11:35 ` Will Deacon 2020-01-23 11:35 ` Will Deacon 2020-01-23 15:25 ` Waiman Long 2020-01-23 15:25 ` Waiman Long 2020-01-23 19:08 ` Waiman Long 2020-01-23 19:08 ` Waiman Long 2020-01-22 19:29 ` Alex Kogan 2020-01-22 19:29 ` Alex Kogan 2020-01-26 0:32 ` Lihao Liang 2020-01-26 0:32 ` Lihao Liang 2020-01-26 1:58 ` Lihao Liang 2020-01-26 1:58 ` Lihao Liang 2020-01-26 1:58 ` Lihao Liang 2020-01-27 16:01 ` Alex Kogan 2020-01-27 16:01 ` Alex Kogan 2020-01-29 1:39 ` Lihao Liang 2020-01-29 1:39 ` Lihao Liang 2020-01-27 6:16 ` Alex Kogan 2020-01-27 6:16 ` Alex Kogan 2020-01-24 22:24 ` Paul E. McKenney 2020-01-24 22:24 ` Paul E. McKenney [not found] ` <6AAE7FC6-F5DE-4067-8BC4-77F27948CD09@oracle.com> 2020-01-25 0:57 ` Paul E. McKenney 2020-01-25 0:57 ` Paul E. McKenney 2020-01-25 1:59 ` Waiman Long 2020-01-25 1:59 ` Waiman Long [not found] ` <adb4fb09-f374-4d64-096b-ba9ad8b35fd5@redhat.com> 2020-01-25 4:58 ` Paul E. McKenney 2020-01-25 4:58 ` Paul E. McKenney 2020-01-25 19:41 ` Waiman Long 2020-01-25 19:41 ` Waiman Long 2020-01-26 15:35 ` Paul E. McKenney 2020-01-26 15:35 ` Paul E. McKenney 2020-01-26 22:42 ` Paul E. McKenney 2020-01-26 22:42 ` Paul E. McKenney 2020-01-26 23:32 ` Paul E. McKenney 2020-01-26 23:32 ` Paul E. McKenney 2020-01-27 6:04 ` Alex Kogan 2020-01-27 6:04 ` Alex Kogan 2020-01-27 14:11 ` Waiman Long 2020-01-27 14:11 ` Waiman Long 2020-01-27 15:09 ` Paul E. McKenney 2020-01-27 15:09 ` Paul E. McKenney [not found] ` <9b3a3f16-5405-b6d1-d023-b85f4aab46dd@redhat.com> 2020-01-27 17:17 ` Waiman Long 2020-01-27 17:17 ` Waiman Long
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