From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ve0-f181.google.com ([209.85.128.181]:39514 "EHLO mail-ve0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932160Ab3CDS4w (ORCPT ); Mon, 4 Mar 2013 13:56:52 -0500 Received: by mail-ve0-f181.google.com with SMTP id d10so5034676vea.12 for ; Mon, 04 Mar 2013 10:56:51 -0800 (PST) From: Jeff Layton To: bfields@fieldses.org Cc: chuck.lever@oracle.com, linux-nfs@vger.kernel.org Subject: [PATCH v2 4/5] nfsd: keep track of the max and average time to search the cache Date: Mon, 4 Mar 2013 13:56:39 -0500 Message-Id: <1362423400-24380-5-git-send-email-jlayton@redhat.com> In-Reply-To: <1362423400-24380-1-git-send-email-jlayton@redhat.com> References: <1362423400-24380-1-git-send-email-jlayton@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Since we're moderately concerned about the potential increase in hash chain lengths, keep a running average of the time and the max time to search. Signed-off-by: Jeff Layton --- fs/nfsd/nfscache.c | 37 +++++++++++++++++++++++++++++++++---- 1 file changed, 33 insertions(+), 4 deletions(-) diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 24ac996..7640e80 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -41,6 +41,15 @@ static unsigned int payload_misses; /* amount of memory (in bytes) currently consumed by the DRC */ static unsigned int drc_mem_usage; +/* total time spent searching the cache */ +static s64 time_in_search; + +/* total number of times we searched the cache */ +static u64 num_searches; + +/* longest time we spent doing a single search */ +static s64 max_search_time; + /* * Calculate the hash index from an XID. */ @@ -318,15 +327,25 @@ 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; + ktime_t start; + s64 delta; + start = ktime_get(); 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; + if (nfsd_cache_match(rqstp, csum, rp)) { + ret = rp; + break; + } } - return NULL; + delta = ktime_to_ns(ktime_sub(ktime_get(), start)); + time_in_search += delta; + max_search_time = max(max_search_time, delta); + ++num_searches; + + return ret; } /* @@ -558,6 +577,14 @@ nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data) return 1; } +static s64 +avg_search_time(void) +{ + if (!num_searches) + return 0; + return time_in_search / num_searches; +} + /* * 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 @@ -574,6 +601,8 @@ 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, "avg search time: %lldns\n", avg_search_time()); + seq_printf(m, "max search time: %lldns\n", max_search_time); spin_unlock(&cache_lock); return 0; } -- 1.7.11.7