From df2d5ae4995b3fb9392b6089b9623d20b6c3a542 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 1 Apr 2013 11:23:35 -0700 Subject: workqueue: map an unbound workqueues to multiple per-node pool_workqueues Currently, an unbound workqueue has only one "current" pool_workqueue associated with it. It may have multple pool_workqueues but only the first pool_workqueue servies new work items. For NUMA affinity, we want to change this so that there are multiple current pool_workqueues serving different NUMA nodes. Introduce workqueue->numa_pwq_tbl[] which is indexed by NUMA node and points to the pool_workqueue to use for each possible node. This replaces first_pwq() in __queue_work() and workqueue_congested(). numa_pwq_tbl[] is currently initialized to point to the same pool_workqueue as first_pwq() so this patch doesn't make any behavior changes. v2: Use rcu_dereference_raw() in unbound_pwq_by_node() as the function may be called only with wq->mutex held. Signed-off-by: Tejun Heo Reviewed-by: Lai Jiangshan --- kernel/workqueue.c | 48 +++++++++++++++++++++++++++++++++++++----------- 1 file changed, 37 insertions(+), 11 deletions(-) (limited to 'kernel/workqueue.c') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 4c53fa216732..170226a24da8 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -257,6 +257,7 @@ struct workqueue_struct { /* hot fields used during command issue, aligned to cacheline */ unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ + struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */ }; static struct kmem_cache *pwq_cache; @@ -525,6 +526,22 @@ static struct pool_workqueue *first_pwq(struct workqueue_struct *wq) pwqs_node); } +/** + * unbound_pwq_by_node - return the unbound pool_workqueue for the given node + * @wq: the target workqueue + * @node: the node ID + * + * This must be called either with pwq_lock held or sched RCU read locked. + * If the pwq needs to be used beyond the locking in effect, the caller is + * responsible for guaranteeing that the pwq stays online. + */ +static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, + int node) +{ + assert_rcu_or_wq_mutex(wq); + return rcu_dereference_raw(wq->numa_pwq_tbl[node]); +} + static unsigned int work_color_to_flags(int color) { return color << WORK_STRUCT_COLOR_SHIFT; @@ -1278,14 +1295,14 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, WARN_ON_ONCE(!is_chained_work(wq))) return; retry: + if (req_cpu == WORK_CPU_UNBOUND) + cpu = raw_smp_processor_id(); + /* pwq which will be used unless @work is executing elsewhere */ - if (!(wq->flags & WQ_UNBOUND)) { - if (cpu == WORK_CPU_UNBOUND) - cpu = raw_smp_processor_id(); + if (!(wq->flags & WQ_UNBOUND)) pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); - } else { - pwq = first_pwq(wq); - } + else + pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); /* * If @work was previously on a different pool, it might still be @@ -1315,8 +1332,8 @@ retry: * pwq is determined and locked. For unbound pools, we could have * raced with pwq release and it could already be dead. If its * refcnt is zero, repeat pwq selection. Note that pwqs never die - * without another pwq replacing it as the first pwq or while a - * work item is executing on it, so the retying is guaranteed to + * without another pwq replacing it in the numa_pwq_tbl or while + * work items are executing on it, so the retrying is guaranteed to * make forward-progress. */ if (unlikely(!pwq->refcnt)) { @@ -3614,6 +3631,8 @@ static void init_and_link_pwq(struct pool_workqueue *pwq, struct worker_pool *pool, struct pool_workqueue **p_last_pwq) { + int node; + BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); pwq->pool = pool; @@ -3640,8 +3659,11 @@ static void init_and_link_pwq(struct pool_workqueue *pwq, /* link in @pwq */ list_add_rcu(&pwq->pwqs_node, &wq->pwqs); - if (wq->flags & WQ_UNBOUND) + if (wq->flags & WQ_UNBOUND) { copy_workqueue_attrs(wq->unbound_attrs, pool->attrs); + for_each_node(node) + rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); + } mutex_unlock(&wq->mutex); } @@ -3761,12 +3783,16 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, struct lock_class_key *key, const char *lock_name, ...) { + size_t tbl_size = 0; va_list args; struct workqueue_struct *wq; struct pool_workqueue *pwq; /* allocate wq and format name */ - wq = kzalloc(sizeof(*wq), GFP_KERNEL); + if (flags & WQ_UNBOUND) + tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]); + + wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); if (!wq) return NULL; @@ -3994,7 +4020,7 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq) if (!(wq->flags & WQ_UNBOUND)) pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); else - pwq = first_pwq(wq); + pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); ret = !list_empty(&pwq->delayed_works); rcu_read_unlock_sched(); -- cgit v1.2.3