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workqueue: remove global_cwq

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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: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Joonsoo Kim <js1304@gmail.com>
This commit is contained in:
Tejun Heo 2013-01-24 11:01:34 -08:00
commit a60dc39c01
2 changed files with 17 additions and 30 deletions
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46
kernel/workqueue.c
View file

@ -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;

1
kernel/workqueue_internal.h
View file

@ -10,7 +10,6 @@
#include <linux/workqueue.h>
#include <linux/kthread.h>
struct global_cwq;
struct worker_pool;
/*