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nfsd: convert num_drc_entries to an atomic_t 

...so we can remove the spinlocking around it.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Trond Myklebust 2014-08-06 13:44:23 -04:00 committed by J. Bruce Fields
parent 11acf6ef3b
commit 31e60f5222
1 changed files with 12 additions and 16 deletions
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28
fs/nfsd/nfscache.c
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@ -47,7 +47,7 @@ static unsigned int drc_hashsize;
*/
/* total number of entries */
static unsigned int num_drc_entries;
static atomic_t num_drc_entries;
/* cache misses due only to checksum comparison failures */
static unsigned int payload_misses;
@ -148,7 +148,7 @@ nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
kfree(rp->c_replvec.iov_base);
}
list_del(&rp->c_lru);
--num_drc_entries;
atomic_dec(&num_drc_entries);
drc_mem_usage -= sizeof(*rp);
kmem_cache_free(drc_slab, rp);
}
@ -167,7 +167,7 @@ int nfsd_reply_cache_init(void)
unsigned int i;
max_drc_entries = nfsd_cache_size_limit();
num_drc_entries = 0;
atomic_set(&num_drc_entries, 0);
hashsize = nfsd_hashsize(max_drc_entries);
maskbits = ilog2(hashsize);
@ -242,7 +242,7 @@ prune_bucket(struct nfsd_drc_bucket *b)
*/
if (rp->c_state == RC_INPROG)
continue;
if (num_drc_entries <= max_drc_entries &&
if (atomic_read(&num_drc_entries) <= max_drc_entries &&
time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
break;
nfsd_reply_cache_free_locked(rp);
@ -290,13 +290,7 @@ cache_cleaner_func(struct work_struct *unused)
static unsigned long
nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
{
unsigned long num;
spin_lock(&cache_lock);
num = num_drc_entries;
spin_unlock(&cache_lock);
return num;
return atomic_read(&num_drc_entries);
}
static unsigned long
@ -386,11 +380,12 @@ nfsd_cache_search(struct nfsd_drc_bucket *b, struct svc_rqst *rqstp,
/* tally hash chain length stats */
if (entries > longest_chain) {
longest_chain = entries;
longest_chain_cachesize = num_drc_entries;
longest_chain_cachesize = atomic_read(&num_drc_entries);
} else if (entries == longest_chain) {
/* prefer to keep the smallest cachesize possible here */
longest_chain_cachesize = min(longest_chain_cachesize,
num_drc_entries);
longest_chain_cachesize = min_t(unsigned int,
longest_chain_cachesize,
atomic_read(&num_drc_entries));
}
return ret;
@ -433,7 +428,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
rp = nfsd_reply_cache_alloc();
spin_lock(&cache_lock);
if (likely(rp)) {
++num_drc_entries;
atomic_inc(&num_drc_entries);
drc_mem_usage += sizeof(*rp);
}
@ -617,7 +612,8 @@ static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
{
spin_lock(&cache_lock);
seq_printf(m, "max entries: %u\n", max_drc_entries);
seq_printf(m, "num entries: %u\n", num_drc_entries);
seq_printf(m, "num entries: %u\n",
atomic_read(&num_drc_entries));
seq_printf(m, "hash buckets: %u\n", 1 << maskbits);
seq_printf(m, "mem usage: %u\n", drc_mem_usage);
seq_printf(m, "cache hits: %u\n", nfsdstats.rchits);