So we can get a feel for how effective the hashing function is.
As Chuck Lever pointed out to me, it's generally acceptable to do
"expensive" stuff when reading the stats since that's a relatively
rare activity.
Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfsd/nfscache.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index a5ac9ab..172e211 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -551,6 +551,25 @@ nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
return 1;
}
+/* Get stats on the hashtable itself */
+static unsigned int
+nfsd_repcache_max_chain_len(void)
+{
+ int i;
+ struct hlist_node *pos;
+ unsigned int max = 0;
+
+ for (i = 0; i < HASHSIZE; ++i) {
+ unsigned int cur = 0;
+
+ hlist_for_each(pos, &cache_hash[i])
+ ++cur;
+ max = max(cur, max);
+ }
+
+ return max;
+}
+
/*
* Note that fields may be added, removed or reordered in the future. Programs
* scraping this file for info should test the labels to ensure they're
@@ -566,6 +585,7 @@ static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
seq_printf(m, "cache misses: %u\n", nfsdstats.rcmisses);
seq_printf(m, "not cached: %u\n", nfsdstats.rcnocache);
seq_printf(m, "checksum misses: %u\n", csum_misses);
+ seq_printf(m, "max chain len: %u\n", nfsd_repcache_max_chain_len());
spin_unlock(&cache_lock);
return 0;
}
--
1.7.11.7
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
