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kernel/include/linux/padata.h
Mathias Krause 0b6b098efc padata: make the sequence counter an atomic_t 
Using a spinlock to atomically increase a counter sounds wrong -- we've
atomic_t for this!

Also move 'seq_nr' to a different cache line than 'lock' to reduce cache
line trashing. This has the nice side effect of decreasing the size of
struct parallel_data from 192 to 128 bytes for a x86-64 build, e.g.
occupying only two instead of three cache lines.

Those changes results in a 5% performance increase on an IPsec test run
using pcrypt.

Btw. the seq_lock spinlock was never explicitly initialized -- one more
reason to get rid of it.

Signed-off-by: Mathias Krause <mathias.krause@secunet.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2013-10-30 12:02:58 +08:00

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/*
* padata.h - header for the padata parallelization interface
*
* Copyright (C) 2008, 2009 secunet Security Networks AG
* Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef PADATA_H
#define PADATA_H
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/notifier.h>
#include <linux/kobject.h>
#define PADATA_CPU_SERIAL 0x01
#define PADATA_CPU_PARALLEL 0x02
/**
* struct padata_priv - Embedded to the users data structure.
*
* @list: List entry, to attach to the padata lists.
* @pd: Pointer to the internal control structure.
* @cb_cpu: Callback cpu for serializatioon.
* @seq_nr: Sequence number of the parallelized data object.
* @info: Used to pass information from the parallel to the serial function.
* @parallel: Parallel execution function.
* @serial: Serial complete function.
*/
struct padata_priv {
struct list_head list;
struct parallel_data *pd;
int cb_cpu;
int info;
void (*parallel)(struct padata_priv *padata);
void (*serial)(struct padata_priv *padata);
};
/**
* struct padata_list
*
* @list: List head.
* @lock: List lock.
*/
struct padata_list {
struct list_head list;
spinlock_t lock;
};
/**
* struct padata_serial_queue - The percpu padata serial queue
*
* @serial: List to wait for serialization after reordering.
* @work: work struct for serialization.
* @pd: Backpointer to the internal control structure.
*/
struct padata_serial_queue {
struct padata_list serial;
struct work_struct work;
struct parallel_data *pd;
};
/**
* struct padata_parallel_queue - The percpu padata parallel queue
*
* @parallel: List to wait for parallelization.
* @reorder: List to wait for reordering after parallel processing.
* @serial: List to wait for serialization after reordering.
* @pwork: work struct for parallelization.
* @swork: work struct for serialization.
* @pd: Backpointer to the internal control structure.
* @work: work struct for parallelization.
* @num_obj: Number of objects that are processed by this cpu.
* @cpu_index: Index of the cpu.
*/
struct padata_parallel_queue {
struct padata_list parallel;
struct padata_list reorder;
struct parallel_data *pd;
struct work_struct work;
atomic_t num_obj;
int cpu_index;
};
/**
* struct padata_cpumask - The cpumasks for the parallel/serial workers
*
* @pcpu: cpumask for the parallel workers.
* @cbcpu: cpumask for the serial (callback) workers.
*/
struct padata_cpumask {
cpumask_var_t pcpu;
cpumask_var_t cbcpu;
};
/**
* struct parallel_data - Internal control structure, covers everything
* that depends on the cpumask in use.
*
* @pinst: padata instance.
* @pqueue: percpu padata queues used for parallelization.
* @squeue: percpu padata queues used for serialuzation.
* @reorder_objects: Number of objects waiting in the reorder queues.
* @refcnt: Number of objects holding a reference on this parallel_data.
* @max_seq_nr: Maximal used sequence number.
* @cpumask: The cpumasks in use for parallel and serial workers.
* @lock: Reorder lock.
* @processed: Number of already processed objects.
* @timer: Reorder timer.
*/
struct parallel_data {
struct padata_instance *pinst;
struct padata_parallel_queue __percpu *pqueue;
struct padata_serial_queue __percpu *squeue;
atomic_t reorder_objects;
atomic_t refcnt;
atomic_t seq_nr;
struct padata_cpumask cpumask;
spinlock_t lock ____cacheline_aligned;
unsigned int processed;
struct timer_list timer;
};
/**
* struct padata_instance - The overall control structure.
*
* @cpu_notifier: cpu hotplug notifier.
* @wq: The workqueue in use.
* @pd: The internal control structure.
* @cpumask: User supplied cpumasks for parallel and serial works.
* @cpumask_change_notifier: Notifiers chain for user-defined notify
* callbacks that will be called when either @pcpu or @cbcpu
* or both cpumasks change.
* @kobj: padata instance kernel object.
* @lock: padata instance lock.
* @flags: padata flags.
*/
struct padata_instance {
struct notifier_block cpu_notifier;
struct workqueue_struct *wq;
struct parallel_data *pd;
struct padata_cpumask cpumask;
struct blocking_notifier_head cpumask_change_notifier;
struct kobject kobj;
struct mutex lock;
u8 flags;
#define PADATA_INIT 1
#define PADATA_RESET 2
#define PADATA_INVALID 4
};
extern struct padata_instance *padata_alloc_possible(
struct workqueue_struct *wq);
extern struct padata_instance *padata_alloc(struct workqueue_struct *wq,
const struct cpumask *pcpumask,
const struct cpumask *cbcpumask);
extern void padata_free(struct padata_instance *pinst);
extern int padata_do_parallel(struct padata_instance *pinst,
struct padata_priv *padata, int cb_cpu);
extern void padata_do_serial(struct padata_priv *padata);
extern int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
cpumask_var_t cpumask);
extern int padata_set_cpumasks(struct padata_instance *pinst,
cpumask_var_t pcpumask,
cpumask_var_t cbcpumask);
extern int padata_add_cpu(struct padata_instance *pinst, int cpu, int mask);
extern int padata_remove_cpu(struct padata_instance *pinst, int cpu, int mask);
extern int padata_start(struct padata_instance *pinst);
extern void padata_stop(struct padata_instance *pinst);
extern int padata_register_cpumask_notifier(struct padata_instance *pinst,
struct notifier_block *nblock);
extern int padata_unregister_cpumask_notifier(struct padata_instance *pinst,
struct notifier_block *nblock);
#endif
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