Commit a60dc39c authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: remove global_cwq 



global_cwq is now nothing but a container for per-cpu standard
worker_pools.  Declare the worker pools directly as
cpu/unbound_std_worker_pools[] and remove global_cwq.

* ____cacheline_aligned_in_smp moved from global_cwq to worker_pool.
  This probably would have made sense even before this change as we
  want each pool to be aligned.

* get_gcwq() is replaced with std_worker_pools() which returns the
  pointer to the standard pool array for a given CPU.

* __alloc_workqueue_key() updated to use get_std_worker_pool() instead
  of open-coding pool determination.

This is part of an effort to remove global_cwq and make worker_pool
the top level abstraction, which in turn will help implementing worker
pools with user-specified attributes.

v2: Joonsoo pointed out that it'd better to align struct worker_pool
    rather than the array so that every pool is aligned.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Joonsoo Kim <js1304@gmail.com>
parent 4e8f0a60

kernel/workqueue.c

+17 −29
Original line number Diff line number Diff line
@@ -144,16 +144,6 @@ struct worker_pool { 


	struct mutex		assoc_mutex;	/* protect POOL_DISASSOCIATED */

	struct ida		worker_ida;	/* L: for worker IDs */

};



/*

 * Global per-cpu workqueue.  There's one and only one for each cpu

 * and all works are queued and processed here regardless of their

 * target workqueues.

 */

struct global_cwq {

	struct worker_pool	pools[NR_STD_WORKER_POOLS];

						/* normal and highpri pools */

} ____cacheline_aligned_in_smp;



/*
@@ -250,8 +240,8 @@ EXPORT_SYMBOL_GPL(system_freezable_wq); 
#include <trace/events/workqueue.h>



#define for_each_std_worker_pool(pool, cpu)				\

	for ((pool) = &get_gcwq((cpu))->pools[0];			\

	     (pool) < &get_gcwq((cpu))->pools[NR_STD_WORKER_POOLS]; (pool)++)

	for ((pool) = &std_worker_pools(cpu)[0];			\

	     (pool) < &std_worker_pools(cpu)[NR_STD_WORKER_POOLS]; (pool)++)



#define for_each_busy_worker(worker, i, pos, pool)			\

	hash_for_each(pool->busy_hash, i, pos, worker, hentry)
@@ -427,19 +417,19 @@ static LIST_HEAD(workqueues); 
static bool workqueue_freezing;		/* W: have wqs started freezing? */



/*

 * The almighty global cpu workqueues.  nr_running is the only field

 * which is expected to be used frequently by other cpus via

 * try_to_wake_up().  Put it in a separate cacheline.

 * The CPU standard worker pools.  nr_running is the only field which is

 * expected to be used frequently by other cpus via try_to_wake_up().  Put

 * it in a separate cacheline.

 */

static DEFINE_PER_CPU(struct global_cwq, global_cwq);

static DEFINE_PER_CPU(struct worker_pool [NR_STD_WORKER_POOLS],

		      cpu_std_worker_pools);

static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_STD_WORKER_POOLS]);



/*

 * Global cpu workqueue and nr_running counter for unbound gcwq.  The pools

 * for online CPUs have POOL_DISASSOCIATED set, and all their workers have

 * WORKER_UNBOUND set.

 * Standard worker pools and nr_running counter for unbound CPU.  The pools

 * have POOL_DISASSOCIATED set, and all workers have WORKER_UNBOUND set.

 */

static struct global_cwq unbound_global_cwq;

static struct worker_pool unbound_std_worker_pools[NR_STD_WORKER_POOLS];

static atomic_t unbound_pool_nr_running[NR_STD_WORKER_POOLS] = {

	[0 ... NR_STD_WORKER_POOLS - 1]	= ATOMIC_INIT(0),	/* always 0 */

};
@@ -450,17 +440,17 @@ static DEFINE_IDR(worker_pool_idr); 


static int worker_thread(void *__worker);



static struct global_cwq *get_gcwq(unsigned int cpu)

static struct worker_pool *std_worker_pools(int cpu)

{

	if (cpu != WORK_CPU_UNBOUND)

		return &per_cpu(global_cwq, cpu);

		return per_cpu(cpu_std_worker_pools, cpu);

	else

		return &unbound_global_cwq;

		return unbound_std_worker_pools;

}



static int std_worker_pool_pri(struct worker_pool *pool)

{

	return pool - get_gcwq(pool->cpu)->pools;

	return pool - std_worker_pools(pool->cpu);

}



/* allocate ID and assign it to @pool */
@@ -487,9 +477,9 @@ static struct worker_pool *worker_pool_by_id(int pool_id) 


static struct worker_pool *get_std_worker_pool(int cpu, bool highpri)

{

	struct global_cwq *gcwq = get_gcwq(cpu);

	struct worker_pool *pools = std_worker_pools(cpu);



	return &gcwq->pools[highpri];

	return &pools[highpri];

}



static atomic_t *get_pool_nr_running(struct worker_pool *pool)
@@ -3269,11 +3259,9 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 


	for_each_cwq_cpu(cpu, wq) {

		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);

		struct global_cwq *gcwq = get_gcwq(cpu);

		int pool_idx = (bool)(flags & WQ_HIGHPRI);



		BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);

		cwq->pool = &gcwq->pools[pool_idx];

		cwq->pool = get_std_worker_pool(cpu, flags & WQ_HIGHPRI);

		cwq->wq = wq;

		cwq->flush_color = -1;

		cwq->max_active = max_active;

kernel/workqueue_internal.h

+0 −1
Original line number Diff line number Diff line
@@ -10,7 +10,6 @@ 
#include <linux/workqueue.h>

#include <linux/kthread.h>



struct global_cwq;

struct worker_pool;



/*

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