diff options
| -rw-r--r-- | fs/nfsd/nfscache.c | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index fd81ca79a002..17cb0d6b9944 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -41,6 +41,12 @@ static unsigned int payload_misses; /* amount of memory (in bytes) currently consumed by the DRC */ static unsigned int drc_mem_usage; +/* longest hash chain seen */ +static unsigned int longest_chain; + +/* size of cache when we saw the longest hash chain */ +static unsigned int longest_chain_cachesize; + /* * Calculate the hash index from an XID. */ @@ -319,15 +325,30 @@ nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp) static struct svc_cacherep * nfsd_cache_search(struct svc_rqst *rqstp, __wsum csum) { - struct svc_cacherep *rp; + struct svc_cacherep *rp, *ret = NULL; struct hlist_head *rh; + unsigned int entries = 0; rh = &cache_hash[request_hash(rqstp->rq_xid)]; hlist_for_each_entry(rp, rh, c_hash) { - if (nfsd_cache_match(rqstp, csum, rp)) - return rp; + ++entries; + if (nfsd_cache_match(rqstp, csum, rp)) { + ret = rp; + break; + } + } + + /* tally hash chain length stats */ + if (entries > longest_chain) { + longest_chain = entries; + longest_chain_cachesize = 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); } - return NULL; + + return ret; } /* @@ -573,6 +594,8 @@ 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, "payload misses: %u\n", payload_misses); + seq_printf(m, "longest chain len: %u\n", longest_chain); + seq_printf(m, "cachesize at longest: %u\n", longest_chain_cachesize); spin_unlock(&cache_lock); return 0; } |