This infrastructure will be used to implement per-client and per-export
serverside stats. Multiple stats objects are kept in a hashtable,
keyed by a string name (e.g. client IP address or export path).
Old entries are pruned from the table using a timer. The function
nfsd_stats_find() can be used to find an entry and create it if
necessary.
Signed-off-by: Greg Banks <gnb@xxxxxxx>
---
fs/nfsd/stats.c | 231 ++++++++++++++++++++++++++++++++++
include/linux/nfsd/debug.h | 1
include/linux/nfsd/stats.h | 43 ++++++
3 files changed, 275 insertions(+)
Index: bfields/fs/nfsd/stats.c
===================================================================
--- bfields.orig/fs/nfsd/stats.c
+++ bfields/fs/nfsd/stats.c
@@ -29,17 +29,29 @@
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/module.h>
+#include <linux/jhash.h>
+#include <linux/list.h>
+#include <linux/swap.h>
+#include <linux/log2.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/stats.h>
#include <linux/nfsd/nfsd.h>
#include <linux/nfsd/stats.h>
+#define NFSDDBG_FACILITY NFSDDBG_STATS
+
+#define hentry_from_hnode(hn) \
+ hlist_entry((hn), nfsd_stats_hentry_t, se_node)
+
struct nfsd_stats nfsdstats;
struct svc_stat nfsd_svcstats = {
.program = &nfsd_program,
};
+int nfsd_stats_enabled = 1;
+int nfsd_stats_prune_period = 2*86400;
+
static int nfsd_proc_show(struct seq_file *seq, void *v)
{
int i;
@@ -98,6 +110,225 @@ static const struct file_operations nfsd
.release = single_release,
};
+
+/*
+ * Stats hash pruning works thus. A scan is run every prune period.
+ * On every scan, hentries with the OLD flag are detached and
+ * a reference dropped (usually that will be the last reference
+ * and the hentry will be deleted). Hentries without the OLD flag
+ * have the OLD flag set; the flag is reset in nfsd_stats_get().
+ * So hentries with active traffic in the last 2 prune periods
+ * are not candidates for pruning.
+ */
+static void nfsd_stats_prune(unsigned long closure)
+{
+ nfsd_stats_hash_t *sh = (nfsd_stats_hash_t *)closure;
+ unsigned int i;
+ nfsd_stats_hentry_t *se;
+ struct hlist_node *hn, *next;
+ struct hlist_head to_be_dropped = HLIST_HEAD_INIT;
+
+ dprintk("nfsd_stats_prune\n");
+
+ if (!down_write_trylock(&sh->sh_sem)) {
+ /* hash is busy...try again in a second */
+ dprintk("nfsd_stats_prune: busy\n");
+ mod_timer(&sh->sh_prune_timer, jiffies + HZ);
+ return;
+ }
+
+ for (i = 0 ; i < sh->sh_size ; i++) {
+ hlist_for_each_entry_safe(se, hn, next, &sh->sh_hash[i], se_node) {
+ if (!test_and_set_bit(NFSD_STATS_HENTRY_OLD, &se->se_flags))
+ continue;
+ hlist_del_init(&se->se_node);
+ hlist_add_head(&se->se_node, &to_be_dropped);
+ }
+ }
+
+ up_write(&sh->sh_sem);
+
+ dprintk("nfsd_stats_prune: deleting\n");
+ hlist_for_each_entry_safe(se, hn, next, &to_be_dropped, se_node)
+ nfsd_stats_put(se);
+
+ mod_timer(&sh->sh_prune_timer, jiffies + nfsd_stats_prune_period * HZ);
+}
+
+/*
+ * Initialise a stats hash. Array size scales with
+ * server memory, as a loose heuristic for how many
+ * clients or exports a server is likely to have.
+ */
+static void nfsd_stats_hash_init(nfsd_stats_hash_t *sh, const char *which)
+{
+ unsigned int nbits;
+ unsigned int i;
+
+ init_rwsem(&sh->sh_sem);
+
+ nbits = 5 + ilog2(totalram_pages >> (30-PAGE_SHIFT));
+ sh->sh_size = (1<<nbits);
+ sh->sh_mask = (sh->sh_size-1);
+
+ sh->sh_hash = kmalloc(sizeof(struct hlist_head) * sh->sh_size, GFP_KERNEL);
+ if (sh->sh_hash == NULL) {
+ printk(KERN_ERR "failed to allocate knfsd %s stats hashtable\n", which);
+ /* struggle on... */
+ return;
+ }
+ printk(KERN_INFO "knfsd %s stats hashtable, %u entries\n", which, sh->sh_size);
+
+ for (i = 0 ; i < sh->sh_size ; i++)
+ INIT_HLIST_HEAD(&sh->sh_hash[i]);
+
+ /* start the prune timer */
+ init_timer(&sh->sh_prune_timer);
+ sh->sh_prune_timer.function = nfsd_stats_prune;
+ sh->sh_prune_timer.expires = jiffies + nfsd_stats_prune_period * HZ;
+ sh->sh_prune_timer.data = (unsigned long)sh;
+}
+
+/*
+ * Destroy a stats hash. Drop what should be the last
+ * reference on all hentries, clean up the timer, and
+ * free the hash array.
+ */
+static void nfsd_stats_hash_destroy(nfsd_stats_hash_t *sh)
+{
+ unsigned int i;
+ nfsd_stats_hentry_t *se;
+
+ del_timer_sync(&sh->sh_prune_timer);
+
+ /* drop the last reference for all remaining hentries */
+ for (i = 0 ; i < sh->sh_size ; i++) {
+ struct hlist_head *hh = &sh->sh_hash[i];
+
+ while (hh->first != NULL) {
+ se = hentry_from_hnode(hh->first);
+ BUG_ON(atomic_read(&se->se_refcount) != 1);
+ nfsd_stats_put(se);
+ }
+ }
+
+ if (sh->sh_hash != NULL) {
+ kfree(sh->sh_hash);
+ }
+}
+
+/*
+ * Find and return a hentry for the given name, with a new refcount,
+ * creating it if necessary. Will only return NULL on OOM or if
+ * stats are disabled. Does it's own locking using the hash rwsem;
+ * may sleep.
+ */
+nfsd_stats_hentry_t *nfsd_stats_find(nfsd_stats_hash_t *sh,
+ const char *name, int len)
+{
+ u32 hash;
+ nfsd_stats_hentry_t *se, *new = NULL;
+ struct hlist_node *hn;
+
+ dprintk("nfsd_stats_find: name %s len %d\n", name, len);
+
+ if (!nfsd_stats_enabled || sh->sh_hash == NULL)
+ return NULL;
+
+
+ /* search the hash table */
+ hash = jhash(name, len, 0xfeedbeef) & sh->sh_mask;
+ down_read(&sh->sh_sem);
+ hlist_for_each_entry(se, hn, &sh->sh_hash[hash], se_node) {
+ if (!strcmp(se->se_name, name)) {
+ /* found matching */
+ dprintk("nfsd_stats_find: found %s\n", se->se_name);
+ nfsd_stats_get(se);
+ up_read(&sh->sh_sem);
+ return se;
+ }
+ }
+ up_read(&sh->sh_sem);
+
+ /* not found, create a new one */
+ dprintk("nfsd_stats_find: allocating new for %s\n", name);
+ new = (nfsd_stats_hentry_t *)kmalloc(sizeof(*new), GFP_KERNEL);
+ if (new == NULL)
+ return NULL;
+ /* initialise */
+
+ new->se_name = kmalloc(len+1, GFP_KERNEL);
+ if (new->se_name == NULL) {
+ kfree(new);
+ return NULL;
+ }
+
+ memcpy(new->se_name, name, len+1);
+ atomic_set(&new->se_refcount, 2);/* 1 for the caller, 1 for the hash */
+ new->se_hash = sh;
+ new->se_flags = 0;
+ INIT_HLIST_NODE(&new->se_node);
+ memset(&new->se_data, 0, sizeof(new->se_data));
+
+ /* attach to the hash datastructure */
+
+ /*
+ * first check to see if we lost a race and some
+ * other thread already added a matching hentry.
+ */
+ down_write(&sh->sh_sem);
+ hlist_for_each_entry(se, hn, &sh->sh_hash[hash], se_node) {
+ if (!strcmp(se->se_name, name)) {
+ /* found matching, use that instead */
+ dprintk("nfsd_stats_find: found(2) %s\n", name);
+ kfree(new->se_name);
+ kfree(new);
+ nfsd_stats_get(se);
+ up_write(&sh->sh_sem);
+ return se;
+ }
+ }
+ /* still not there, insert new one into the hash */
+ hlist_add_head(&new->se_node, &sh->sh_hash[hash]);
+
+ up_write(&sh->sh_sem);
+ return new;
+}
+
+/*
+ * Drop a reference to a hentry, deleting the hentry if this
+ * was the last reference. Does it's own locking using the
+ * hash rwsem; may sleep.
+ */
+void
+nfsd_stats_put(nfsd_stats_hentry_t *se)
+{
+ nfsd_stats_hash_t *sh = se->se_hash;
+
+ if (!atomic_dec_and_test(&se->se_refcount))
+ return;
+
+ /* just dropped the last reference */
+ down_write(&sh->sh_sem);
+
+ if (atomic_read(&se->se_refcount)) {
+ /*
+ * We lost a race getting the write lock, and
+ * now there's a reference again. Whatever.
+ */
+ goto out_unlock;
+ }
+
+ dprintk("nfsd_stats_put: freeing %s\n", se->se_name);
+ hlist_del(&se->se_node);
+ kfree(se->se_name);
+ kfree(se);
+
+out_unlock:
+ up_write(&sh->sh_sem);
+}
+
+
void
nfsd_stat_init(void)
{
Index: bfields/include/linux/nfsd/stats.h
===================================================================
--- bfields.orig/include/linux/nfsd/stats.h
+++ bfields/include/linux/nfsd/stats.h
@@ -40,6 +40,37 @@ struct nfsd_stats {
};
+struct nfsd_op_stats {
+ /* nothing to see here, yet */
+};
+
+
+typedef struct nfsd_stats_hash nfsd_stats_hash_t;
+typedef struct nfsd_stats_hentry nfsd_stats_hentry_t;
+
+/* Entry in the export and client stats hashtables */
+struct nfsd_stats_hentry {
+ struct hlist_node se_node; /* links hash chains */
+ char *se_name;
+ atomic_t se_refcount; /* 1 for each user + 1 for hash */
+#define NFSD_STATS_HENTRY_OLD 0
+ unsigned long se_flags;
+ nfsd_stats_hash_t *se_hash;
+ struct nfsd_op_stats se_data;
+};
+
+/*
+ * Hashtable structure for export and client stats.
+ * Table width is chosen at boot time to scale with
+ * the size of the server.
+ */
+struct nfsd_stats_hash {
+ struct rw_semaphore sh_sem;
+ unsigned int sh_size;
+ unsigned int sh_mask;
+ struct hlist_head *sh_hash;
+ struct timer_list sh_prune_timer;
+};
extern struct nfsd_stats nfsdstats;
extern struct svc_stat nfsd_svcstats;
@@ -47,5 +78,17 @@ extern struct svc_stat nfsd_svcstats;
void nfsd_stat_init(void);
void nfsd_stat_shutdown(void);
+extern nfsd_stats_hentry_t *nfsd_stats_find(nfsd_stats_hash_t *,
+ const char *name, int len);
+static inline void
+nfsd_stats_get(nfsd_stats_hentry_t *se)
+{
+ atomic_inc(&se->se_refcount);
+ clear_bit(NFSD_STATS_HENTRY_OLD, &se->se_flags);
+}
+extern void nfsd_stats_put(nfsd_stats_hentry_t *se);
+
+
+
#endif /* __KERNEL__ */
#endif /* LINUX_NFSD_STATS_H */
Index: bfields/include/linux/nfsd/debug.h
===================================================================
--- bfields.orig/include/linux/nfsd/debug.h
+++ bfields/include/linux/nfsd/debug.h
@@ -32,6 +32,7 @@
#define NFSDDBG_REPCACHE 0x0080
#define NFSDDBG_XDR 0x0100
#define NFSDDBG_LOCKD 0x0200
+#define NFSDDBG_STATS 0x0400
#define NFSDDBG_ALL 0x7FFF
#define NFSDDBG_NOCHANGE 0xFFFF
--
Greg
--
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