From bedd4b61a46d0398192a08fbe6821d1ac65aba84 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 6 Aug 2014 13:44:21 -0400 Subject: [PATCH] nfsd: convert the lru list into a per-bucket thing Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- fs/nfsd/nfscache.c | 73 +++++++++++++++++++++++++++++++--------------- 1 file changed, 50 insertions(+), 23 deletions(-) diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index c74bcd628c4f..c01f44eb7fe4 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -29,10 +29,10 @@ struct nfsd_drc_bucket { struct hlist_head cache_hash; + struct list_head lru_head; }; static struct nfsd_drc_bucket *drc_hashtbl; -static struct list_head lru_head; static struct kmem_cache *drc_slab; /* max number of entries allowed in the cache */ @@ -40,6 +40,7 @@ static unsigned int max_drc_entries; /* number of significant bits in the hash value */ static unsigned int maskbits; +static unsigned int drc_hashsize; /* * Stats and other tracking of on the duplicate reply cache. All of these and @@ -167,8 +168,8 @@ nfsd_reply_cache_free(struct svc_cacherep *rp) int nfsd_reply_cache_init(void) { unsigned int hashsize; + unsigned int i; - INIT_LIST_HEAD(&lru_head); max_drc_entries = nfsd_cache_size_limit(); num_drc_entries = 0; hashsize = nfsd_hashsize(max_drc_entries); @@ -183,6 +184,9 @@ int nfsd_reply_cache_init(void) drc_hashtbl = kcalloc(hashsize, sizeof(*drc_hashtbl), GFP_KERNEL); if (!drc_hashtbl) goto out_nomem; + for (i = 0; i < hashsize; i++) + INIT_LIST_HEAD(&drc_hashtbl[i].lru_head); + drc_hashsize = hashsize; return 0; out_nomem: @@ -194,17 +198,22 @@ out_nomem: void nfsd_reply_cache_shutdown(void) { struct svc_cacherep *rp; + unsigned int i; unregister_shrinker(&nfsd_reply_cache_shrinker); cancel_delayed_work_sync(&cache_cleaner); - while (!list_empty(&lru_head)) { - rp = list_entry(lru_head.next, struct svc_cacherep, c_lru); - nfsd_reply_cache_free_locked(rp); + for (i = 0; i < drc_hashsize; i++) { + struct list_head *head = &drc_hashtbl[i].lru_head; + while (!list_empty(head)) { + rp = list_first_entry(head, struct svc_cacherep, c_lru); + nfsd_reply_cache_free_locked(rp); + } } kfree (drc_hashtbl); drc_hashtbl = NULL; + drc_hashsize = 0; if (drc_slab) { kmem_cache_destroy(drc_slab); @@ -217,10 +226,10 @@ void nfsd_reply_cache_shutdown(void) * not already scheduled. */ static void -lru_put_end(struct svc_cacherep *rp) +lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp) { rp->c_timestamp = jiffies; - list_move_tail(&rp->c_lru, &lru_head); + list_move_tail(&rp->c_lru, &b->lru_head); schedule_delayed_work(&cache_cleaner, RC_EXPIRE); } @@ -234,17 +243,13 @@ hash_refile(struct nfsd_drc_bucket *b, struct svc_cacherep *rp) hlist_add_head(&rp->c_hash, &b->cache_hash); } -/* - * Walk the LRU list and prune off entries that are older than RC_EXPIRE. - * Also prune the oldest ones when the total exceeds the max number of entries. - */ static long -prune_cache_entries(void) +prune_bucket(struct nfsd_drc_bucket *b) { struct svc_cacherep *rp, *tmp; long freed = 0; - list_for_each_entry_safe(rp, tmp, &lru_head, c_lru) { + list_for_each_entry_safe(rp, tmp, &b->lru_head, c_lru) { /* * Don't free entries attached to calls that are still * in-progress, but do keep scanning the list. @@ -257,16 +262,33 @@ prune_cache_entries(void) nfsd_reply_cache_free_locked(rp); freed++; } + return freed; +} + +/* + * Walk the LRU list and prune off entries that are older than RC_EXPIRE. + * Also prune the oldest ones when the total exceeds the max number of entries. + */ +static long +prune_cache_entries(void) +{ + unsigned int i; + long freed = 0; + bool cancel = true; + + for (i = 0; i < drc_hashsize; i++) { + struct nfsd_drc_bucket *b = &drc_hashtbl[i]; + + freed += prune_bucket(b); + if (!list_empty(&b->lru_head)) + cancel = false; + } /* - * Conditionally rearm the job. If we cleaned out the list, then - * cancel any pending run (since there won't be any work to do). - * Otherwise, we rearm the job or modify the existing one to run in - * RC_EXPIRE since we just ran the pruner. + * Conditionally rearm the job to run in RC_EXPIRE since we just + * ran the pruner. */ - if (list_empty(&lru_head)) - cancel_delayed_work(&cache_cleaner); - else + if (!cancel) mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE); return freed; } @@ -458,7 +480,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) rp->c_csum = csum; hash_refile(b, rp); - lru_put_end(rp); + lru_put_end(b, rp); /* release any buffer */ if (rp->c_type == RC_REPLBUFF) { @@ -475,7 +497,7 @@ found_entry: nfsdstats.rchits++; /* We found a matching entry which is either in progress or done. */ age = jiffies - rp->c_timestamp; - lru_put_end(rp); + lru_put_end(b, rp); rtn = RC_DROPIT; /* Request being processed or excessive rexmits */ @@ -530,12 +552,17 @@ nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) { struct svc_cacherep *rp = rqstp->rq_cacherep; struct kvec *resv = &rqstp->rq_res.head[0], *cachv; + u32 hash; + struct nfsd_drc_bucket *b; int len; size_t bufsize = 0; if (!rp) return; + hash = nfsd_cache_hash(rp->c_xid); + b = &drc_hashtbl[hash]; + len = resv->iov_len - ((char*)statp - (char*)resv->iov_base); len >>= 2; @@ -568,7 +595,7 @@ nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) } spin_lock(&cache_lock); drc_mem_usage += bufsize; - lru_put_end(rp); + lru_put_end(b, rp); rp->c_secure = rqstp->rq_secure; rp->c_type = cachetype; rp->c_state = RC_DONE; -- 2.20.1