From: Trond Myklebust <trond.myklebust@primarydata.com>
To: Bruce Fields <bfields@fieldses.org>
Cc: linux-nfs@vger.kernel.org
Subject: [PATCH 4/6] nfsd: convert num_drc_entries to an atomic_t
Date: Sun, 3 Aug 2014 13:06:02 -0400 [thread overview]
Message-ID: <1407085564-3227-5-git-send-email-trond.myklebust@primarydata.com> (raw)
In-Reply-To: <1407085564-3227-4-git-send-email-trond.myklebust@primarydata.com>
...so we can remove the spinlocking around it.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
fs/nfsd/nfscache.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 8abec475f80f..dc909091349b 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -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);
--
1.9.3
next prev parent reply other threads:[~2014-08-03 17:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-03 17:05 [PATCH 0/6] NFS DRC scalability patches Trond Myklebust
2014-08-03 17:05 ` [PATCH 1/6] nfsd: Clean up drc cache in preparation for global spinlock elimination Trond Myklebust
2014-08-03 17:06 ` [PATCH 2/6] nfsd: convert the lru list into a per-bucket thing Trond Myklebust
2014-08-03 17:06 ` [PATCH 3/6] nfsd: Remove the cache_hash list Trond Myklebust
2014-08-03 17:06 ` Trond Myklebust [this message]
2014-08-03 17:06 ` [PATCH 5/6] nfsd: split DRC global spinlock into per-bucket locks Trond Myklebust
2014-08-03 17:06 ` [PATCH 6/6] nfsd: Reorder nfsd_cache_match to check more powerful discriminators first Trond Myklebust
2014-08-04 11:44 ` [PATCH 5/6] nfsd: split DRC global spinlock into per-bucket locks Jeff Layton
2014-08-04 11:45 ` [PATCH 0/6] NFS DRC scalability patches Jeff Layton
2014-08-05 20:51 ` Bruce Fields
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