Make fscache operation to use only workqueue instead of combination of workqueue and slow-work. FSCACHE_OP_SLOW is dropped and FSCACHE_OP_FAST is renamed to FSCACHE_OP_ASYNC and uses newly added fscache_op_wq workqueue to execute op->processor(). fscache_operation_init_slow() is dropped and fscache_operation_init() now takes @processor argument directly.
* Unbound workqueue is used.
* fscache_retrieval_work() is no longer necessary as OP_ASYNC now does the equivalent thing.
* sysctl fscache.operation_max_active added to control concurrency. The default value is nr_cpus clamped between 2 and WQ_UNBOUND_MAX_ACTIVE.
* debugfs support is dropped for now. Tracing API based debug facility is planned to be added.
Signed-off-by: Tejun Heo tj@kernel.org Cc: David Howells dhowells@redhat.com --- fs/cachefiles/rdwr.c | 4 +- fs/fscache/internal.h | 1 + fs/fscache/main.c | 23 ++++++++++++++ fs/fscache/operation.c | 67 +++++------------------------------------ fs/fscache/page.c | 36 +++++----------------- include/linux/fscache-cache.h | 37 +++++++---------------- 6 files changed, 53 insertions(+), 115 deletions(-)
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c index 0f0d41f..0e3c092 100644 --- a/fs/cachefiles/rdwr.c +++ b/fs/cachefiles/rdwr.c @@ -422,7 +422,7 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op, shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
op->op.flags &= FSCACHE_OP_KEEP_FLAGS; - op->op.flags |= FSCACHE_OP_FAST; + op->op.flags |= FSCACHE_OP_ASYNC; op->op.processor = cachefiles_read_copier;
pagevec_init(&pagevec, 0); @@ -729,7 +729,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op, pagevec_init(&pagevec, 0);
op->op.flags &= FSCACHE_OP_KEEP_FLAGS; - op->op.flags |= FSCACHE_OP_FAST; + op->op.flags |= FSCACHE_OP_ASYNC; op->op.processor = cachefiles_read_copier;
INIT_LIST_HEAD(&backpages); diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 6e0b5fb..6a02644 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -83,6 +83,7 @@ extern unsigned fscache_defer_create; extern unsigned fscache_debug; extern struct kobject *fscache_root; extern struct workqueue_struct *fscache_object_wq; +extern struct workqueue_struct *fscache_op_wq; DECLARE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
static inline bool fscache_object_congested(void) diff --git a/fs/fscache/main.c b/fs/fscache/main.c index bb8d4c3..44d13dd 100644 --- a/fs/fscache/main.c +++ b/fs/fscache/main.c @@ -42,11 +42,13 @@ MODULE_PARM_DESC(fscache_debug,
struct kobject *fscache_root; struct workqueue_struct *fscache_object_wq; +struct workqueue_struct *fscache_op_wq;
DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
/* these values serve as lower bounds, will be adjusted in fscache_init() */ static unsigned fscache_object_max_active = 4; +static unsigned fscache_op_max_active = 2;
#ifdef CONFIG_SYSCTL static struct ctl_table_header *fscache_sysctl_header; @@ -74,6 +76,14 @@ ctl_table fscache_sysctls[] = { .proc_handler = fscache_max_active_sysctl, .extra1 = &fscache_object_wq, }, + { + .procname = "operation_max_active", + .data = &fscache_op_max_active, + .maxlen = sizeof(unsigned), + .mode = 0644, + .proc_handler = fscache_max_active_sysctl, + .extra1 = &fscache_op_wq, + }, {} };
@@ -110,6 +120,16 @@ static int __init fscache_init(void) if (!fscache_object_wq) goto error_object_wq;
+ fscache_op_max_active = + clamp_val(fscache_object_max_active / 2, + fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE); + + ret = -ENOMEM; + fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND, + fscache_op_max_active); + if (!fscache_op_wq) + goto error_op_wq; + for_each_possible_cpu(cpu) init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
@@ -152,6 +172,8 @@ error_sysctl: #endif fscache_proc_cleanup(); error_proc: + destroy_workqueue(fscache_op_wq); +error_op_wq: destroy_workqueue(fscache_object_wq); error_object_wq: slow_work_unregister_user(THIS_MODULE); @@ -172,6 +194,7 @@ static void __exit fscache_exit(void) kmem_cache_destroy(fscache_cookie_jar); unregister_sysctl_table(fscache_sysctl_header); fscache_proc_cleanup(); + destroy_workqueue(fscache_op_wq); destroy_workqueue(fscache_object_wq); slow_work_unregister_user(THIS_MODULE); printk(KERN_NOTICE "FS-Cache: Unloaded\n"); diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index f17ceca..b9f34ea 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -42,16 +42,12 @@ void fscache_enqueue_operation(struct fscache_operation *op)
fscache_stat(&fscache_n_op_enqueue); switch (op->flags & FSCACHE_OP_TYPE) { - case FSCACHE_OP_FAST: - _debug("queue fast"); + case FSCACHE_OP_ASYNC: + _debug("queue async"); atomic_inc(&op->usage); - if (!schedule_work(&op->fast_work)) + if (!queue_work(fscache_op_wq, &op->work)) fscache_put_operation(op); break; - case FSCACHE_OP_SLOW: - _debug("queue slow"); - slow_work_enqueue(&op->slow_work); - break; case FSCACHE_OP_MYTHREAD: _debug("queue for caller's attention"); break; @@ -455,36 +451,13 @@ void fscache_operation_gc(struct work_struct *work) }
/* - * allow the slow work item processor to get a ref on an operation - */ -static int fscache_op_get_ref(struct slow_work *work) -{ - struct fscache_operation *op = - container_of(work, struct fscache_operation, slow_work); - - atomic_inc(&op->usage); - return 0; -} - -/* - * allow the slow work item processor to discard a ref on an operation - */ -static void fscache_op_put_ref(struct slow_work *work) -{ - struct fscache_operation *op = - container_of(work, struct fscache_operation, slow_work); - - fscache_put_operation(op); -} - -/* - * execute an operation using the slow thread pool to provide processing context - * - the caller holds a ref to this object, so we don't need to hold one + * execute an operation using fs_op_wq to provide processing context - + * the caller holds a ref to this object, so we don't need to hold one */ -static void fscache_op_execute(struct slow_work *work) +void fscache_op_work_func(struct work_struct *work) { struct fscache_operation *op = - container_of(work, struct fscache_operation, slow_work); + container_of(work, struct fscache_operation, work); unsigned long start;
_enter("{OBJ%x OP%x,%d}", @@ -494,31 +467,7 @@ static void fscache_op_execute(struct slow_work *work) start = jiffies; op->processor(op); fscache_hist(fscache_ops_histogram, start); + fscache_put_operation(op);
_leave(""); } - -/* - * describe an operation for slow-work debugging - */ -#ifdef CONFIG_SLOW_WORK_DEBUG -static void fscache_op_desc(struct slow_work *work, struct seq_file *m) -{ - struct fscache_operation *op = - container_of(work, struct fscache_operation, slow_work); - - seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx", - op->object->debug_id, op->debug_id, - op->name, op->state, op->flags); -} -#endif - -const struct slow_work_ops fscache_op_slow_work_ops = { - .owner = THIS_MODULE, - .get_ref = fscache_op_get_ref, - .put_ref = fscache_op_put_ref, - .execute = fscache_op_execute, -#ifdef CONFIG_SLOW_WORK_DEBUG - .desc = fscache_op_desc, -#endif -}; diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 723b889..41c441c 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -105,7 +105,7 @@ bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
page_busy: /* we might want to wait here, but that could deadlock the allocator as - * the slow-work threads writing to the cache may all end up sleeping + * the work threads writing to the cache may all end up sleeping * on memory allocation */ fscache_stat(&fscache_n_store_vmscan_busy); return false; @@ -188,9 +188,8 @@ int __fscache_attr_changed(struct fscache_cookie *cookie) return -ENOMEM; }
- fscache_operation_init(op, NULL); - fscache_operation_init_slow(op, fscache_attr_changed_op); - op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE); + fscache_operation_init(op, fscache_attr_changed_op, NULL); + op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE); fscache_set_op_name(op, "Attr");
spin_lock(&cookie->lock); @@ -218,24 +217,6 @@ nobufs: EXPORT_SYMBOL(__fscache_attr_changed);
/* - * handle secondary execution given to a retrieval op on behalf of the - * cache - */ -static void fscache_retrieval_work(struct work_struct *work) -{ - struct fscache_retrieval *op = - container_of(work, struct fscache_retrieval, op.fast_work); - unsigned long start; - - _enter("{OP%x}", op->op.debug_id); - - start = jiffies; - op->op.processor(&op->op); - fscache_hist(fscache_ops_histogram, start); - fscache_put_operation(&op->op); -} - -/* * release a retrieval op reference */ static void fscache_release_retrieval_op(struct fscache_operation *_op) @@ -269,13 +250,12 @@ static struct fscache_retrieval *fscache_alloc_retrieval( return NULL; }
- fscache_operation_init(&op->op, fscache_release_retrieval_op); + fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op); op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING); op->mapping = mapping; op->end_io_func = end_io_func; op->context = context; op->start_time = jiffies; - INIT_WORK(&op->op.fast_work, fscache_retrieval_work); INIT_LIST_HEAD(&op->to_do); fscache_set_op_name(&op->op, "Retr"); return op; @@ -795,9 +775,9 @@ int __fscache_write_page(struct fscache_cookie *cookie, if (!op) goto nomem;
- fscache_operation_init(&op->op, fscache_release_write_op); - fscache_operation_init_slow(&op->op, fscache_write_op); - op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING); + fscache_operation_init(&op->op, fscache_write_op, + fscache_release_write_op); + op->op.flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_WAITING); fscache_set_op_name(&op->op, "Write1");
ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM); @@ -852,7 +832,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, fscache_stat(&fscache_n_store_ops); fscache_stat(&fscache_n_stores_ok);
- /* the slow work queue now carries its own ref on the object */ + /* the work queue now carries its own ref on the object */ fscache_put_operation(&op->op); _leave(" = 0"); return 0; diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h index 27c8df5..17ed9c1 100644 --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -77,18 +77,14 @@ typedef void (*fscache_operation_release_t)(struct fscache_operation *op); typedef void (*fscache_operation_processor_t)(struct fscache_operation *op);
struct fscache_operation { - union { - struct work_struct fast_work; /* record for fast ops */ - struct slow_work slow_work; /* record for (very) slow ops */ - }; + struct work_struct work; /* record for async ops */ struct list_head pend_link; /* link in object->pending_ops */ struct fscache_object *object; /* object to be operated upon */
unsigned long flags; #define FSCACHE_OP_TYPE 0x000f /* operation type */ -#define FSCACHE_OP_FAST 0x0001 /* - fast op, processor may not sleep for disk */ -#define FSCACHE_OP_SLOW 0x0002 /* - (very) slow op, processor may sleep for disk */ -#define FSCACHE_OP_MYTHREAD 0x0003 /* - processing is done be issuing thread, not pool */ +#define FSCACHE_OP_ASYNC 0x0001 /* - async op, processor may sleep for disk */ +#define FSCACHE_OP_MYTHREAD 0x0002 /* - processing is done be issuing thread, not pool */ #define FSCACHE_OP_WAITING 4 /* cleared when op is woken */ #define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */ #define FSCACHE_OP_DEAD 6 /* op is now dead */ @@ -106,7 +102,8 @@ struct fscache_operation { /* operation releaser */ fscache_operation_release_t release;
-#ifdef CONFIG_SLOW_WORK_DEBUG +#ifdef CONFIG_WORKQUEUE_DEBUGFS + struct work_struct put_work; /* work to delay operation put */ const char *name; /* operation name */ const char *state; /* operation state */ #define fscache_set_op_name(OP, N) do { (OP)->name = (N); } while(0) @@ -118,7 +115,7 @@ struct fscache_operation { };
extern atomic_t fscache_op_debug_id; -extern const struct slow_work_ops fscache_op_slow_work_ops; +extern void fscache_op_work_func(struct work_struct *work);
extern void fscache_enqueue_operation(struct fscache_operation *); extern void fscache_put_operation(struct fscache_operation *); @@ -129,33 +126,21 @@ extern void fscache_put_operation(struct fscache_operation *); * @release: The release function to assign * * Do basic initialisation of an operation. The caller must still set flags, - * object, either fast_work or slow_work if necessary, and processor if needed. + * object and processor if needed. */ static inline void fscache_operation_init(struct fscache_operation *op, - fscache_operation_release_t release) + fscache_operation_processor_t processor, + fscache_operation_release_t release) { + INIT_WORK(&op->work, fscache_op_work_func); atomic_set(&op->usage, 1); op->debug_id = atomic_inc_return(&fscache_op_debug_id); + op->processor = processor; op->release = release; INIT_LIST_HEAD(&op->pend_link); fscache_set_op_state(op, "Init"); }
-/** - * fscache_operation_init_slow - Do additional initialisation of a slow op - * @op: The operation to initialise - * @processor: The processor function to assign - * - * Do additional initialisation of an operation as required for slow work. - */ -static inline -void fscache_operation_init_slow(struct fscache_operation *op, - fscache_operation_processor_t processor) -{ - op->processor = processor; - slow_work_init(&op->slow_work, &fscache_op_slow_work_ops); -} - /* * data read operation */