On Feb 15, 2013, at 12:23 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> For presenting statistics relating to duplicate reply cache.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/nfsd/cache.h | 1 +
> fs/nfsd/nfscache.c | 37 +++++++++++++++++++++++++++++++++----
> fs/nfsd/nfsctl.c | 9 +++++++++
> 3 files changed, 43 insertions(+), 4 deletions(-)
>
> diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h
> index 87fd141..d5c5b3e 100644
> --- a/fs/nfsd/cache.h
> +++ b/fs/nfsd/cache.h
> @@ -82,6 +82,7 @@ int nfsd_reply_cache_init(void);
> void nfsd_reply_cache_shutdown(void);
> int nfsd_cache_lookup(struct svc_rqst *);
> void nfsd_cache_update(struct svc_rqst *, int, __be32 *);
> +int nfsd_reply_cache_stats_open(struct inode *, struct file *);
>
> #ifdef CONFIG_NFSD_V4
> void nfsd4_set_statp(struct svc_rqst *rqstp, __be32 *statp);
> diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
> index ad1d069..b155afa 100644
> --- a/fs/nfsd/nfscache.c
> +++ b/fs/nfsd/nfscache.c
> @@ -23,12 +23,17 @@
> static struct hlist_head * cache_hash;
> static struct list_head lru_head;
> static struct kmem_cache *drc_slab;
> -static unsigned int num_drc_entries;
> -static unsigned int max_drc_entries;
> -static unsigned int drc_mem_usage;
> -static unsigned int csum_misses;
>
> /*
> + * Stats on the duplicate reply cache code. All of these and the "rc" fields
> + * in nfsdstats are protected by the cache_lock
> + */
> +static unsigned int num_drc_entries; /* number of entries */
> +static unsigned int max_drc_entries; /* max number of entries */
> +static unsigned int drc_mem_usage; /* memory used by cache */
> +static unsigned int csum_misses; /* cache misses due only to
> + csum comparison failures */
> +/*
> * Calculate the hash index from an XID.
> */
> static inline u32 request_hash(u32 xid)
> @@ -545,3 +550,27 @@ nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
> vec->iov_len += data->iov_len;
> return 1;
> }
> +
> +/*
> + * 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
> + * getting the correct field.
> + */
> +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, "mem usage: %u\n", drc_mem_usage);
> + seq_printf(m, "cache hits: %u\n", nfsdstats.rchits);
> + 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);
> + spin_unlock(&cache_lock);
> + return 0;
> +}
Would it be hard to add a statistic that quantified the distribution of entries in the cache hash table? Something like "maximum length of cache hash chain" ?
> +
> +int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, nfsd_reply_cache_stats_show, NULL);
> +}
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index 29c3f0d..5dea5af 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -35,6 +35,7 @@ enum {
> NFSD_Threads,
> NFSD_Pool_Threads,
> NFSD_Pool_Stats,
> + NFSD_Reply_Cache_Stats,
> NFSD_Versions,
> NFSD_Ports,
> NFSD_MaxBlkSize,
> @@ -194,6 +195,13 @@ static const struct file_operations pool_stats_operations = {
> .owner = THIS_MODULE,
> };
>
> +static struct file_operations reply_cache_stats_operations = {
> + .open = nfsd_reply_cache_stats_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +
> /*----------------------------------------------------------------------------*/
> /*
> * payload - write methods
> @@ -1024,6 +1032,7 @@ static int nfsd_fill_super(struct super_block * sb, void * data, int silent)
> [NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
> [NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR},
> [NFSD_Pool_Stats] = {"pool_stats", &pool_stats_operations, S_IRUGO},
> + [NFSD_Reply_Cache_Stats] = {"reply_cache_stats", &reply_cache_stats_operations, S_IRUGO},
> [NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR},
> [NFSD_Ports] = {"portlist", &transaction_ops, S_IWUSR|S_IRUGO},
> [NFSD_MaxBlkSize] = {"max_block_size", &transaction_ops, S_IWUSR|S_IRUGO},
> --
> 1.7.11.7
>
> --
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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