![Daniel Jordan](/assets/img/avatar_default.png)
padata allocates per-CPU, per-instance work structs for parallel jobs. A
do_parallel call assigns a job to a sequence number and hashes the number
to a CPU, where the job will eventually run using the corresponding work.
This approach fit with how padata used to bind a job to each CPU
round-robin, makes less sense after commit bfde23ce20
("padata: unbind
parallel jobs from specific CPUs") because a work isn't bound to a
particular CPU anymore, and isn't needed at all for multithreaded jobs
because they don't have sequence numbers.
Replace the per-CPU works with a preallocated pool, which allows sharing
them between existing padata users and the upcoming multithreaded user.
The pool will also facilitate setting NUMA-aware concurrency limits with
later users.
The pool is sized according to the number of possible CPUs. With this
limit, MAX_OBJ_NUM no longer makes sense, so remove it.
If the global pool is exhausted, a parallel job is run in the current task
instead to throttle a system trying to do too much in parallel.
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-4-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
181 lines
5.5 KiB
C
181 lines
5.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* padata.h - header for the padata parallelization interface
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*
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* Copyright (C) 2008, 2009 secunet Security Networks AG
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* Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
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*/
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#ifndef PADATA_H
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#define PADATA_H
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#include <linux/compiler_types.h>
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#include <linux/workqueue.h>
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/kobject.h>
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#define PADATA_CPU_SERIAL 0x01
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#define PADATA_CPU_PARALLEL 0x02
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/**
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* struct padata_priv - Represents one job
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*
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* @list: List entry, to attach to the padata lists.
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* @pd: Pointer to the internal control structure.
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* @cb_cpu: Callback cpu for serializatioon.
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* @seq_nr: Sequence number of the parallelized data object.
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* @info: Used to pass information from the parallel to the serial function.
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* @parallel: Parallel execution function.
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* @serial: Serial complete function.
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*/
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struct padata_priv {
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struct list_head list;
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struct parallel_data *pd;
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int cb_cpu;
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unsigned int seq_nr;
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int info;
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void (*parallel)(struct padata_priv *padata);
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void (*serial)(struct padata_priv *padata);
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};
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/**
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* struct padata_list - one per work type per CPU
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*
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* @list: List head.
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* @lock: List lock.
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*/
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struct padata_list {
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struct list_head list;
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spinlock_t lock;
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};
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/**
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* struct padata_serial_queue - The percpu padata serial queue
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*
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* @serial: List to wait for serialization after reordering.
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* @work: work struct for serialization.
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* @pd: Backpointer to the internal control structure.
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*/
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struct padata_serial_queue {
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struct padata_list serial;
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struct work_struct work;
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struct parallel_data *pd;
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};
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/**
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* struct padata_parallel_queue - The percpu padata parallel queue
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*
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* @reorder: List to wait for reordering after parallel processing.
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* @num_obj: Number of objects that are processed by this cpu.
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*/
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struct padata_parallel_queue {
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struct padata_list reorder;
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atomic_t num_obj;
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};
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/**
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* struct padata_cpumask - The cpumasks for the parallel/serial workers
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*
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* @pcpu: cpumask for the parallel workers.
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* @cbcpu: cpumask for the serial (callback) workers.
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*/
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struct padata_cpumask {
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cpumask_var_t pcpu;
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cpumask_var_t cbcpu;
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};
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/**
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* struct parallel_data - Internal control structure, covers everything
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* that depends on the cpumask in use.
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*
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* @ps: padata_shell object.
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* @pqueue: percpu padata queues used for parallelization.
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* @squeue: percpu padata queues used for serialuzation.
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* @refcnt: Number of objects holding a reference on this parallel_data.
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* @seq_nr: Sequence number of the parallelized data object.
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* @processed: Number of already processed objects.
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* @cpu: Next CPU to be processed.
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* @cpumask: The cpumasks in use for parallel and serial workers.
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* @reorder_work: work struct for reordering.
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* @lock: Reorder lock.
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*/
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struct parallel_data {
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struct padata_shell *ps;
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struct padata_parallel_queue __percpu *pqueue;
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struct padata_serial_queue __percpu *squeue;
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atomic_t refcnt;
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unsigned int seq_nr;
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unsigned int processed;
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int cpu;
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struct padata_cpumask cpumask;
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struct work_struct reorder_work;
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spinlock_t ____cacheline_aligned lock;
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};
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/**
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* struct padata_shell - Wrapper around struct parallel_data, its
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* purpose is to allow the underlying control structure to be replaced
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* on the fly using RCU.
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*
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* @pinst: padat instance.
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* @pd: Actual parallel_data structure which may be substituted on the fly.
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* @opd: Pointer to old pd to be freed by padata_replace.
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* @list: List entry in padata_instance list.
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*/
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struct padata_shell {
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struct padata_instance *pinst;
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struct parallel_data __rcu *pd;
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struct parallel_data *opd;
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struct list_head list;
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};
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/**
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* struct padata_instance - The overall control structure.
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*
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* @cpu_online_node: Linkage for CPU online callback.
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* @cpu_dead_node: Linkage for CPU offline callback.
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* @parallel_wq: The workqueue used for parallel work.
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* @serial_wq: The workqueue used for serial work.
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* @pslist: List of padata_shell objects attached to this instance.
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* @cpumask: User supplied cpumasks for parallel and serial works.
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* @rcpumask: Actual cpumasks based on user cpumask and cpu_online_mask.
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* @kobj: padata instance kernel object.
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* @lock: padata instance lock.
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* @flags: padata flags.
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*/
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struct padata_instance {
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struct hlist_node cpu_online_node;
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struct hlist_node cpu_dead_node;
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struct workqueue_struct *parallel_wq;
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struct workqueue_struct *serial_wq;
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struct list_head pslist;
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struct padata_cpumask cpumask;
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struct padata_cpumask rcpumask;
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struct kobject kobj;
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struct mutex lock;
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u8 flags;
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#define PADATA_INIT 1
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#define PADATA_RESET 2
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#define PADATA_INVALID 4
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};
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#ifdef CONFIG_PADATA
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extern void __init padata_init(void);
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#else
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static inline void __init padata_init(void) {}
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#endif
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extern struct padata_instance *padata_alloc_possible(const char *name);
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extern void padata_free(struct padata_instance *pinst);
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extern struct padata_shell *padata_alloc_shell(struct padata_instance *pinst);
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extern void padata_free_shell(struct padata_shell *ps);
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extern int padata_do_parallel(struct padata_shell *ps,
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struct padata_priv *padata, int *cb_cpu);
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extern void padata_do_serial(struct padata_priv *padata);
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extern int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
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cpumask_var_t cpumask);
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extern int padata_start(struct padata_instance *pinst);
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extern void padata_stop(struct padata_instance *pinst);
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#endif
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