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NFSD: Report average age of filecache items

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This is a measure of how long items stay in the filecache, to help
assess how efficient the cache is.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2022-07-08 14:24:12 -04:00
parent d63293272a
commit 904940e94a
2 changed files with 11 additions and 1 deletions
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11
fs/nfsd/filecache.c
View File

@ -45,6 +45,7 @@ struct nfsd_fcache_bucket {
static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions);
static DEFINE_PER_CPU(unsigned long, nfsd_file_releases);
static DEFINE_PER_CPU(unsigned long, nfsd_file_total_age);
struct nfsd_fcache_disposal {
struct work_struct work;
@ -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;
@ -195,9 +197,11 @@ 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);
this_cpu_add(nfsd_file_total_age, age);
trace_nfsd_file_put_final(nf);
if (nf->nf_mark)
@ -1055,7 +1059,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
{
unsigned long hits = 0, acquisitions = 0, releases = 0;
unsigned int i, count = 0, longest = 0;
unsigned long lru = 0;
unsigned long lru = 0, total_age = 0;
/*
* No need for spinlocks here since we're not terribly interested in
@ -1076,6 +1080,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
hits += per_cpu(nfsd_file_cache_hits, i);
acquisitions += per_cpu(nfsd_file_acquisitions, i);
releases += per_cpu(nfsd_file_releases, i);
total_age += per_cpu(nfsd_file_total_age, i);
}
seq_printf(m, "total entries: %u\n", count);
@ -1084,6 +1089,10 @@ 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", total_age / releases);
else
seq_printf(m, "mean age (ms): -\n");
return 0;
}

1
fs/nfsd/filecache.h
View File

@ -44,6 +44,7 @@ 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);