This is a measure of how long items stay in the filecache, to help
assess how efficient the cache is.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/filecache.c | 9 +++++++++
fs/nfsd/filecache.h | 1 +
2 files changed, 10 insertions(+)
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index f735f91e576b..6f48528c6284 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -61,6 +61,7 @@ static struct list_lru nfsd_file_lru;
static long nfsd_file_lru_flags;
static struct fsnotify_group *nfsd_file_fsnotify_group;
static atomic_long_t nfsd_filecache_count;
+static atomic_long_t nfsd_file_total_age;
static struct delayed_work nfsd_filecache_laundrette;
static void nfsd_file_gc(void);
@@ -178,6 +179,7 @@ nfsd_file_alloc(struct inode *inode, unsigned int may, unsigned int hashval,
if (nf) {
INIT_HLIST_NODE(&nf->nf_node);
INIT_LIST_HEAD(&nf->nf_lru);
+ nf->nf_birthtime = ktime_get();
nf->nf_file = NULL;
nf->nf_cred = get_current_cred();
nf->nf_net = net;
@@ -201,9 +203,11 @@ nfsd_file_alloc(struct inode *inode, unsigned int may, unsigned int hashval,
static bool
nfsd_file_free(struct nfsd_file *nf)
{
+ s64 age = ktime_to_ms(ktime_sub(ktime_get(), nf->nf_birthtime));
bool flush = false;
this_cpu_inc(nfsd_file_releases);
+ atomic_long_add(age, &nfsd_file_total_age);
trace_nfsd_file_put_final(nf);
if (nf->nf_mark)
@@ -1102,6 +1106,11 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
seq_printf(m, "cache hits: %lu\n", hits);
seq_printf(m, "acquisitions: %lu\n", acquisitions);
seq_printf(m, "releases: %lu\n", releases);
+ if (releases)
+ seq_printf(m, "mean age (ms): %ld\n",
+ atomic_long_read(&nfsd_file_total_age) / releases);
+ else
+ seq_printf(m, "mean age (ms): -\n");
return 0;
}
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 1da0c79a5580..d0c42619dc10 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -46,6 +46,7 @@ struct nfsd_file {
refcount_t nf_ref;
unsigned char nf_may;
struct nfsd_file_mark *nf_mark;
+ ktime_t nf_birthtime;
};
int nfsd_file_cache_init(void);
