diff options
| -rw-r--r-- | net/rds/ib_rdma.c | 214 | ||||
| -rw-r--r-- | net/rds/xlist.h | 110 |
2 files changed, 282 insertions, 42 deletions
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c index 64b5ede037c8..8c40391de5a2 100644 --- a/net/rds/ib_rdma.c +++ b/net/rds/ib_rdma.c @@ -36,7 +36,10 @@ #include "rds.h" #include "ib.h" +#include "xlist.h" +static DEFINE_PER_CPU(unsigned long, clean_list_grace); +#define CLEAN_LIST_BUSY_BIT 0 /* * This is stored as mr->r_trans_private. @@ -45,7 +48,11 @@ struct rds_ib_mr { struct rds_ib_device *device; struct rds_ib_mr_pool *pool; struct ib_fmr *fmr; - struct list_head list; + + struct xlist_head xlist; + + /* unmap_list is for freeing */ + struct list_head unmap_list; unsigned int remap_count; struct scatterlist *sg; @@ -61,12 +68,14 @@ struct rds_ib_mr_pool { struct mutex flush_lock; /* serialize fmr invalidate */ struct work_struct flush_worker; /* flush worker */ - spinlock_t list_lock; /* protect variables below */ atomic_t item_count; /* total # of MRs */ atomic_t dirty_count; /* # dirty of MRs */ - struct list_head drop_list; /* MRs that have reached their max_maps limit */ - struct list_head free_list; /* unused MRs */ - struct list_head clean_list; /* unused & unamapped MRs */ + + struct xlist_head drop_list; /* MRs that have reached their max_maps limit */ + struct xlist_head free_list; /* unused MRs */ + struct xlist_head clean_list; /* global unused & unamapped MRs */ + wait_queue_head_t flush_wait; + atomic_t free_pinned; /* memory pinned by free MRs */ unsigned long max_items; unsigned long max_items_soft; @@ -74,7 +83,7 @@ struct rds_ib_mr_pool { struct ib_fmr_attr fmr_attr; }; -static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all); +static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all, struct rds_ib_mr **); static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr); static void rds_ib_mr_pool_flush_worker(struct work_struct *work); @@ -212,11 +221,11 @@ struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev) if (!pool) return ERR_PTR(-ENOMEM); - INIT_LIST_HEAD(&pool->free_list); - INIT_LIST_HEAD(&pool->drop_list); - INIT_LIST_HEAD(&pool->clean_list); + INIT_XLIST_HEAD(&pool->free_list); + INIT_XLIST_HEAD(&pool->drop_list); + INIT_XLIST_HEAD(&pool->clean_list); mutex_init(&pool->flush_lock); - spin_lock_init(&pool->list_lock); + init_waitqueue_head(&pool->flush_wait); INIT_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker); pool->fmr_attr.max_pages = fmr_message_size; @@ -246,27 +255,50 @@ void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_co void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool) { cancel_work_sync(&pool->flush_worker); - rds_ib_flush_mr_pool(pool, 1); + rds_ib_flush_mr_pool(pool, 1, NULL); WARN_ON(atomic_read(&pool->item_count)); WARN_ON(atomic_read(&pool->free_pinned)); kfree(pool); } +static void refill_local(struct rds_ib_mr_pool *pool, struct xlist_head *xl, + struct rds_ib_mr **ibmr_ret) +{ + struct xlist_head *ibmr_xl; + ibmr_xl = xlist_del_head_fast(xl); + *ibmr_ret = list_entry(ibmr_xl, struct rds_ib_mr, xlist); +} + static inline struct rds_ib_mr *rds_ib_reuse_fmr(struct rds_ib_mr_pool *pool) { struct rds_ib_mr *ibmr = NULL; - unsigned long flags; + struct xlist_head *ret; + unsigned long *flag; - spin_lock_irqsave(&pool->list_lock, flags); - if (!list_empty(&pool->clean_list)) { - ibmr = list_entry(pool->clean_list.next, struct rds_ib_mr, list); - list_del_init(&ibmr->list); - } - spin_unlock_irqrestore(&pool->list_lock, flags); + preempt_disable(); + flag = &__get_cpu_var(clean_list_grace); + set_bit(CLEAN_LIST_BUSY_BIT, flag); + ret = xlist_del_head(&pool->clean_list); + if (ret) + ibmr = list_entry(ret, struct rds_ib_mr, xlist); + clear_bit(CLEAN_LIST_BUSY_BIT, flag); + preempt_enable(); return ibmr; } +static inline void wait_clean_list_grace(void) +{ + int cpu; + unsigned long *flag; + + for_each_online_cpu(cpu) { + flag = &per_cpu(clean_list_grace, cpu); + while (test_bit(CLEAN_LIST_BUSY_BIT, flag)) + cpu_relax(); + } +} + static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev) { struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool; @@ -299,7 +331,9 @@ static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev) /* We do have some empty MRs. Flush them out. */ rds_ib_stats_inc(s_ib_rdma_mr_pool_wait); - rds_ib_flush_mr_pool(pool, 0); + rds_ib_flush_mr_pool(pool, 0, &ibmr); + if (ibmr) + return ibmr; } ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL, rdsibdev_to_node(rds_ibdev)); @@ -494,33 +528,109 @@ static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int fr } /* + * given an xlist of mrs, put them all into the list_head for more processing + */ +static void xlist_append_to_list(struct xlist_head *xlist, struct list_head *list) +{ + struct rds_ib_mr *ibmr; + struct xlist_head splice; + struct xlist_head *cur; + struct xlist_head *next; + + splice.next = NULL; + xlist_splice(xlist, &splice); + cur = splice.next; + while (cur) { + next = cur->next; + ibmr = list_entry(cur, struct rds_ib_mr, xlist); + list_add_tail(&ibmr->unmap_list, list); + cur = next; + } +} + +/* + * this takes a list head of mrs and turns it into an xlist of clusters. + * each cluster has an xlist of MR_CLUSTER_SIZE mrs that are ready for + * reuse. + */ +static void list_append_to_xlist(struct rds_ib_mr_pool *pool, + struct list_head *list, struct xlist_head *xlist, + struct xlist_head **tail_ret) +{ + struct rds_ib_mr *ibmr; + struct xlist_head *cur_mr = xlist; + struct xlist_head *tail_mr = NULL; + + list_for_each_entry(ibmr, list, unmap_list) { + tail_mr = &ibmr->xlist; + tail_mr->next = NULL; + cur_mr->next = tail_mr; + cur_mr = tail_mr; + } + *tail_ret = tail_mr; +} + +/* * Flush our pool of MRs. * At a minimum, all currently unused MRs are unmapped. * If the number of MRs allocated exceeds the limit, we also try * to free as many MRs as needed to get back to this limit. */ -static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all) +static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, + int free_all, struct rds_ib_mr **ibmr_ret) { struct rds_ib_mr *ibmr, *next; + struct xlist_head clean_xlist; + struct xlist_head *clean_tail; LIST_HEAD(unmap_list); LIST_HEAD(fmr_list); unsigned long unpinned = 0; - unsigned long flags; unsigned int nfreed = 0, ncleaned = 0, free_goal; int ret = 0; rds_ib_stats_inc(s_ib_rdma_mr_pool_flush); - mutex_lock(&pool->flush_lock); + if (ibmr_ret) { + DEFINE_WAIT(wait); + while(!mutex_trylock(&pool->flush_lock)) { + ibmr = rds_ib_reuse_fmr(pool); + if (ibmr) { + *ibmr_ret = ibmr; + finish_wait(&pool->flush_wait, &wait); + goto out_nolock; + } + + prepare_to_wait(&pool->flush_wait, &wait, + TASK_UNINTERRUPTIBLE); + if (xlist_empty(&pool->clean_list)) + schedule(); + + ibmr = rds_ib_reuse_fmr(pool); + if (ibmr) { + *ibmr_ret = ibmr; + finish_wait(&pool->flush_wait, &wait); + goto out_nolock; + } + } + finish_wait(&pool->flush_wait, &wait); + } else + mutex_lock(&pool->flush_lock); + + if (ibmr_ret) { + ibmr = rds_ib_reuse_fmr(pool); + if (ibmr) { + *ibmr_ret = ibmr; + goto out; + } + } - spin_lock_irqsave(&pool->list_lock, flags); /* Get the list of all MRs to be dropped. Ordering matters - - * we want to put drop_list ahead of free_list. */ - list_splice_init(&pool->free_list, &unmap_list); - list_splice_init(&pool->drop_list, &unmap_list); + * we want to put drop_list ahead of free_list. + */ + xlist_append_to_list(&pool->drop_list, &unmap_list); + xlist_append_to_list(&pool->free_list, &unmap_list); if (free_all) - list_splice_init(&pool->clean_list, &unmap_list); - spin_unlock_irqrestore(&pool->list_lock, flags); + xlist_append_to_list(&pool->clean_list, &unmap_list); free_goal = rds_ib_flush_goal(pool, free_all); @@ -528,19 +638,20 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all) goto out; /* String all ib_mr's onto one list and hand them to ib_unmap_fmr */ - list_for_each_entry(ibmr, &unmap_list, list) + list_for_each_entry(ibmr, &unmap_list, unmap_list) list_add(&ibmr->fmr->list, &fmr_list); + ret = ib_unmap_fmr(&fmr_list); if (ret) printk(KERN_WARNING "RDS/IB: ib_unmap_fmr failed (err=%d)\n", ret); /* Now we can destroy the DMA mapping and unpin any pages */ - list_for_each_entry_safe(ibmr, next, &unmap_list, list) { + list_for_each_entry_safe(ibmr, next, &unmap_list, unmap_list) { unpinned += ibmr->sg_len; __rds_ib_teardown_mr(ibmr); if (nfreed < free_goal || ibmr->remap_count >= pool->fmr_attr.max_maps) { rds_ib_stats_inc(s_ib_rdma_mr_free); - list_del(&ibmr->list); + list_del(&ibmr->unmap_list); ib_dealloc_fmr(ibmr->fmr); kfree(ibmr); nfreed++; @@ -548,9 +659,27 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all) ncleaned++; } - spin_lock_irqsave(&pool->list_lock, flags); - list_splice(&unmap_list, &pool->clean_list); - spin_unlock_irqrestore(&pool->list_lock, flags); + if (!list_empty(&unmap_list)) { + /* we have to make sure that none of the things we're about + * to put on the clean list would race with other cpus trying + * to pull items off. The xlist would explode if we managed to + * remove something from the clean list and then add it back again + * while another CPU was spinning on that same item in xlist_del_head. + * + * This is pretty unlikely, but just in case wait for an xlist grace period + * here before adding anything back into the clean list. + */ + wait_clean_list_grace(); + + list_append_to_xlist(pool, &unmap_list, &clean_xlist, &clean_tail); + if (ibmr_ret) + refill_local(pool, &clean_xlist, ibmr_ret); + + /* refill_local may have emptied our list */ + if (!xlist_empty(&clean_xlist)) + xlist_add(clean_xlist.next, clean_tail, &pool->clean_list); + + } atomic_sub(unpinned, &pool->free_pinned); atomic_sub(ncleaned, &pool->dirty_count); @@ -558,6 +687,9 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all) out: mutex_unlock(&pool->flush_lock); + if (waitqueue_active(&pool->flush_wait)) + wake_up(&pool->flush_wait); +out_nolock: return ret; } @@ -565,7 +697,7 @@ static void rds_ib_mr_pool_flush_worker(struct work_struct *work) { struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker); - rds_ib_flush_mr_pool(pool, 0); + rds_ib_flush_mr_pool(pool, 0, NULL); } void rds_ib_free_mr(void *trans_private, int invalidate) @@ -573,20 +705,17 @@ void rds_ib_free_mr(void *trans_private, int invalidate) struct rds_ib_mr *ibmr = trans_private; struct rds_ib_device *rds_ibdev = ibmr->device; struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool; - unsigned long flags; rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len); /* Return it to the pool's free list */ - spin_lock_irqsave(&pool->list_lock, flags); if (ibmr->remap_count >= pool->fmr_attr.max_maps) - list_add(&ibmr->list, &pool->drop_list); + xlist_add(&ibmr->xlist, &ibmr->xlist, &pool->drop_list); else - list_add(&ibmr->list, &pool->free_list); + xlist_add(&ibmr->xlist, &ibmr->xlist, &pool->free_list); atomic_add(ibmr->sg_len, &pool->free_pinned); atomic_inc(&pool->dirty_count); - spin_unlock_irqrestore(&pool->list_lock, flags); /* If we've pinned too many pages, request a flush */ if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned || @@ -595,7 +724,7 @@ void rds_ib_free_mr(void *trans_private, int invalidate) if (invalidate) { if (likely(!in_interrupt())) { - rds_ib_flush_mr_pool(pool, 0); + rds_ib_flush_mr_pool(pool, 0, NULL); } else { /* We get here if the user created a MR marked * as use_once and invalidate at the same time. */ @@ -614,7 +743,7 @@ void rds_ib_flush_mrs(void) struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool; if (pool) - rds_ib_flush_mr_pool(pool, 0); + rds_ib_flush_mr_pool(pool, 0, NULL); } } @@ -659,3 +788,4 @@ void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents, rds_ib_dev_put(rds_ibdev); return ibmr; } + diff --git a/net/rds/xlist.h b/net/rds/xlist.h new file mode 100644 index 000000000000..8c21aca49d50 --- /dev/null +++ b/net/rds/xlist.h @@ -0,0 +1,110 @@ +#ifndef _LINUX_XLIST_H +#define _LINUX_XLIST_H + +#include <linux/stddef.h> +#include <linux/poison.h> +#include <linux/prefetch.h> +#include <asm/system.h> + +struct xlist_head { + struct xlist_head *next; +}; + +/* + * XLIST_PTR_TAIL can be used to prevent double insertion. See + * xlist_protect() + */ +#define XLIST_PTR_TAIL ((struct xlist_head *)0x1) + +static inline void xlist_add(struct xlist_head *new, struct xlist_head *tail, struct xlist_head *head) +{ + struct xlist_head *cur; + struct xlist_head *check; + + while (1) { + cur = head->next; + tail->next = cur; + check = cmpxchg(&head->next, cur, new); + if (check == cur) + break; + } +} + +/* + * To avoid duplicate insertion by two CPUs of the same xlist item + * you can call xlist_protect. It will stuff XLIST_PTR_TAIL + * into the entry->next pointer with xchg, and only return 1 + * if there was a NULL there before. + * + * if xlist_protect returns zero, someone else is busy working + * on this entry. Getting a NULL into the entry in a race + * free manner is the caller's job. + */ +static inline int xlist_protect(struct xlist_head *entry) +{ + struct xlist_head *val; + + val = xchg(&entry->next, XLIST_PTR_TAIL); + if (val == NULL) + return 1; + return 0; +} + +static inline struct xlist_head *xlist_del_head(struct xlist_head *head) +{ + struct xlist_head *cur; + struct xlist_head *check; + struct xlist_head *next; + + while (1) { + cur = head->next; + if (!cur) + goto out; + + if (cur == XLIST_PTR_TAIL) { + cur = NULL; + goto out; + } + + next = cur->next; + check = cmpxchg(&head->next, cur, next); + if (check == cur) + goto out; + } +out: + return cur; +} + +static inline struct xlist_head *xlist_del_head_fast(struct xlist_head *head) +{ + struct xlist_head *cur; + + cur = head->next; + if (!cur || cur == XLIST_PTR_TAIL) + return NULL; + + head->next = cur->next; + return cur; +} + +static inline void xlist_splice(struct xlist_head *list, + struct xlist_head *head) +{ + struct xlist_head *cur; + + WARN_ON(head->next); + cur = xchg(&list->next, NULL); + head->next = cur; +} + +static inline void INIT_XLIST_HEAD(struct xlist_head *list) +{ + list->next = NULL; +} + +static inline int xlist_empty(struct xlist_head *head) +{ + return head->next == NULL || head->next == XLIST_PTR_TAIL; +} + +#endif |