diff options
author | Daniel Jordan <daniel.m.jordan@oracle.com> | 2020-06-04 01:59:39 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-04 06:09:45 +0300 |
commit | 4611ce22468895acd61fee9ac1da810d60617d9a (patch) | |
tree | e5f71eeb19df9a835455734e6ec059433bf5854e /kernel/padata.c | |
parent | f1b192b117cd418bacf42a9583d7a01855a18fe5 (diff) |
padata: allocate work structures for parallel jobs from a pool
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 bfde23ce200e6 ("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>
Diffstat (limited to 'kernel/padata.c')
-rw-r--r-- | kernel/padata.c | 118 |
1 files changed, 77 insertions, 41 deletions
diff --git a/kernel/padata.c b/kernel/padata.c index 0c5f4f78f2c2..d779a73d4d92 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -32,7 +32,15 @@ #include <linux/sysfs.h> #include <linux/rcupdate.h> -#define MAX_OBJ_NUM 1000 +struct padata_work { + struct work_struct pw_work; + struct list_head pw_list; /* padata_free_works linkage */ + void *pw_data; +}; + +static DEFINE_SPINLOCK(padata_works_lock); +static struct padata_work *padata_works; +static LIST_HEAD(padata_free_works); static void padata_free_pd(struct parallel_data *pd); @@ -58,30 +66,44 @@ static int padata_cpu_hash(struct parallel_data *pd, unsigned int seq_nr) return padata_index_to_cpu(pd, cpu_index); } -static void padata_parallel_worker(struct work_struct *parallel_work) +static struct padata_work *padata_work_alloc(void) { - struct padata_parallel_queue *pqueue; - LIST_HEAD(local_list); + struct padata_work *pw; - local_bh_disable(); - pqueue = container_of(parallel_work, - struct padata_parallel_queue, work); + lockdep_assert_held(&padata_works_lock); - spin_lock(&pqueue->parallel.lock); - list_replace_init(&pqueue->parallel.list, &local_list); - spin_unlock(&pqueue->parallel.lock); + if (list_empty(&padata_free_works)) + return NULL; /* No more work items allowed to be queued. */ - while (!list_empty(&local_list)) { - struct padata_priv *padata; + pw = list_first_entry(&padata_free_works, struct padata_work, pw_list); + list_del(&pw->pw_list); + return pw; +} - padata = list_entry(local_list.next, - struct padata_priv, list); +static void padata_work_init(struct padata_work *pw, work_func_t work_fn, + void *data) +{ + INIT_WORK(&pw->pw_work, work_fn); + pw->pw_data = data; +} - list_del_init(&padata->list); +static void padata_work_free(struct padata_work *pw) +{ + lockdep_assert_held(&padata_works_lock); + list_add(&pw->pw_list, &padata_free_works); +} - padata->parallel(padata); - } +static void padata_parallel_worker(struct work_struct *parallel_work) +{ + struct padata_work *pw = container_of(parallel_work, struct padata_work, + pw_work); + struct padata_priv *padata = pw->pw_data; + local_bh_disable(); + padata->parallel(padata); + spin_lock(&padata_works_lock); + padata_work_free(pw); + spin_unlock(&padata_works_lock); local_bh_enable(); } @@ -105,9 +127,9 @@ int padata_do_parallel(struct padata_shell *ps, struct padata_priv *padata, int *cb_cpu) { struct padata_instance *pinst = ps->pinst; - int i, cpu, cpu_index, target_cpu, err; - struct padata_parallel_queue *queue; + int i, cpu, cpu_index, err; struct parallel_data *pd; + struct padata_work *pw; rcu_read_lock_bh(); @@ -135,25 +157,25 @@ int padata_do_parallel(struct padata_shell *ps, if ((pinst->flags & PADATA_RESET)) goto out; - if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM) - goto out; - - err = 0; atomic_inc(&pd->refcnt); padata->pd = pd; padata->cb_cpu = *cb_cpu; - padata->seq_nr = atomic_inc_return(&pd->seq_nr); - target_cpu = padata_cpu_hash(pd, padata->seq_nr); - padata->cpu = target_cpu; - queue = per_cpu_ptr(pd->pqueue, target_cpu); - - spin_lock(&queue->parallel.lock); - list_add_tail(&padata->list, &queue->parallel.list); - spin_unlock(&queue->parallel.lock); + rcu_read_unlock_bh(); - queue_work(pinst->parallel_wq, &queue->work); + spin_lock(&padata_works_lock); + padata->seq_nr = ++pd->seq_nr; + pw = padata_work_alloc(); + spin_unlock(&padata_works_lock); + if (pw) { + padata_work_init(pw, padata_parallel_worker, padata); + queue_work(pinst->parallel_wq, &pw->pw_work); + } else { + /* Maximum works limit exceeded, run in the current task. */ + padata->parallel(padata); + } + return 0; out: rcu_read_unlock_bh(); @@ -324,8 +346,9 @@ static void padata_serial_worker(struct work_struct *serial_work) void padata_do_serial(struct padata_priv *padata) { struct parallel_data *pd = padata->pd; + int hashed_cpu = padata_cpu_hash(pd, padata->seq_nr); struct padata_parallel_queue *pqueue = per_cpu_ptr(pd->pqueue, - padata->cpu); + hashed_cpu); struct padata_priv *cur; spin_lock(&pqueue->reorder.lock); @@ -416,8 +439,6 @@ static void padata_init_pqueues(struct parallel_data *pd) pqueue = per_cpu_ptr(pd->pqueue, cpu); __padata_list_init(&pqueue->reorder); - __padata_list_init(&pqueue->parallel); - INIT_WORK(&pqueue->work, padata_parallel_worker); atomic_set(&pqueue->num_obj, 0); } } @@ -451,7 +472,7 @@ static struct parallel_data *padata_alloc_pd(struct padata_shell *ps) padata_init_pqueues(pd); padata_init_squeues(pd); - atomic_set(&pd->seq_nr, -1); + pd->seq_nr = -1; atomic_set(&pd->refcnt, 1); spin_lock_init(&pd->lock); pd->cpu = cpumask_first(pd->cpumask.pcpu); @@ -1053,6 +1074,7 @@ EXPORT_SYMBOL(padata_free_shell); void __init padata_init(void) { + unsigned int i, possible_cpus; #ifdef CONFIG_HOTPLUG_CPU int ret; @@ -1064,13 +1086,27 @@ void __init padata_init(void) ret = cpuhp_setup_state_multi(CPUHP_PADATA_DEAD, "padata:dead", NULL, padata_cpu_dead); - if (ret < 0) { - cpuhp_remove_multi_state(hp_online); - goto err; - } + if (ret < 0) + goto remove_online_state; +#endif + + possible_cpus = num_possible_cpus(); + padata_works = kmalloc_array(possible_cpus, sizeof(struct padata_work), + GFP_KERNEL); + if (!padata_works) + goto remove_dead_state; + + for (i = 0; i < possible_cpus; ++i) + list_add(&padata_works[i].pw_list, &padata_free_works); return; + +remove_dead_state: +#ifdef CONFIG_HOTPLUG_CPU + cpuhp_remove_multi_state(CPUHP_PADATA_DEAD); +remove_online_state: + cpuhp_remove_multi_state(hp_online); err: - pr_warn("padata: initialization failed\n"); #endif + pr_warn("padata: initialization failed\n"); } |