2015-11-04 16:02:35

by Jeff Layton

[permalink] [raw]
Subject: [PATCH] nfsd: remove recurring workqueue job to clean DRC

We have a shrinker, we clean out the cache when nfsd is shut down, and
prune the chains on each request. A recurring workqueue job seems like
unnecessary overhead. Just remove it.

Signed-off-by: Jeff Layton <[email protected]>
---
fs/nfsd/nfscache.c | 26 --------------------------
1 file changed, 26 deletions(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 46ec934f5dee..8af64b6ffe91 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -63,7 +63,6 @@ static unsigned int longest_chain;
static unsigned int longest_chain_cachesize;

static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
-static void cache_cleaner_func(struct work_struct *unused);
static unsigned long nfsd_reply_cache_count(struct shrinker *shrink,
struct shrink_control *sc);
static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink,
@@ -76,13 +75,6 @@ static struct shrinker nfsd_reply_cache_shrinker = {
};

/*
- * locking for the reply cache:
- * A cache entry is "single use" if c_state == RC_INPROG
- * Otherwise, it when accessing _prev or _next, the lock must be held.
- */
-static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func);
-
-/*
* Put a cap on the size of the DRC based on the amount of available
* low memory in the machine.
*
@@ -203,7 +195,6 @@ void nfsd_reply_cache_shutdown(void)
unsigned int i;

unregister_shrinker(&nfsd_reply_cache_shrinker);
- cancel_delayed_work_sync(&cache_cleaner);

for (i = 0; i < drc_hashsize; i++) {
struct list_head *head = &drc_hashtbl[i].lru_head;
@@ -232,7 +223,6 @@ lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
{
rp->c_timestamp = jiffies;
list_move_tail(&rp->c_lru, &b->lru_head);
- schedule_delayed_work(&cache_cleaner, RC_EXPIRE);
}

static long
@@ -266,7 +256,6 @@ prune_cache_entries(void)
{
unsigned int i;
long freed = 0;
- bool cancel = true;

for (i = 0; i < drc_hashsize; i++) {
struct nfsd_drc_bucket *b = &drc_hashtbl[i];
@@ -275,26 +264,11 @@ prune_cache_entries(void)
continue;
spin_lock(&b->cache_lock);
freed += prune_bucket(b);
- if (!list_empty(&b->lru_head))
- cancel = false;
spin_unlock(&b->cache_lock);
}
-
- /*
- * Conditionally rearm the job to run in RC_EXPIRE since we just
- * ran the pruner.
- */
- if (!cancel)
- mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE);
return freed;
}

-static void
-cache_cleaner_func(struct work_struct *unused)
-{
- prune_cache_entries();
-}
-
static unsigned long
nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
{
--
2.4.3



2015-11-05 21:31:37

by J. Bruce Fields

[permalink] [raw]
Subject: Re: [PATCH] nfsd: remove recurring workqueue job to clean DRC

On Wed, Nov 04, 2015 at 11:02:29AM -0500, Jeff Layton wrote:
> We have a shrinker, we clean out the cache when nfsd is shut down, and
> prune the chains on each request. A recurring workqueue job seems like
> unnecessary overhead. Just remove it.

Thanks, applying.--b.

>
> Signed-off-by: Jeff Layton <[email protected]>
> ---
> fs/nfsd/nfscache.c | 26 --------------------------
> 1 file changed, 26 deletions(-)
>
> diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
> index 46ec934f5dee..8af64b6ffe91 100644
> --- a/fs/nfsd/nfscache.c
> +++ b/fs/nfsd/nfscache.c
> @@ -63,7 +63,6 @@ static unsigned int longest_chain;
> static unsigned int longest_chain_cachesize;
>
> static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
> -static void cache_cleaner_func(struct work_struct *unused);
> static unsigned long nfsd_reply_cache_count(struct shrinker *shrink,
> struct shrink_control *sc);
> static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink,
> @@ -76,13 +75,6 @@ static struct shrinker nfsd_reply_cache_shrinker = {
> };
>
> /*
> - * locking for the reply cache:
> - * A cache entry is "single use" if c_state == RC_INPROG
> - * Otherwise, it when accessing _prev or _next, the lock must be held.
> - */
> -static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func);
> -
> -/*
> * Put a cap on the size of the DRC based on the amount of available
> * low memory in the machine.
> *
> @@ -203,7 +195,6 @@ void nfsd_reply_cache_shutdown(void)
> unsigned int i;
>
> unregister_shrinker(&nfsd_reply_cache_shrinker);
> - cancel_delayed_work_sync(&cache_cleaner);
>
> for (i = 0; i < drc_hashsize; i++) {
> struct list_head *head = &drc_hashtbl[i].lru_head;
> @@ -232,7 +223,6 @@ lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
> {
> rp->c_timestamp = jiffies;
> list_move_tail(&rp->c_lru, &b->lru_head);
> - schedule_delayed_work(&cache_cleaner, RC_EXPIRE);
> }
>
> static long
> @@ -266,7 +256,6 @@ prune_cache_entries(void)
> {
> unsigned int i;
> long freed = 0;
> - bool cancel = true;
>
> for (i = 0; i < drc_hashsize; i++) {
> struct nfsd_drc_bucket *b = &drc_hashtbl[i];
> @@ -275,26 +264,11 @@ prune_cache_entries(void)
> continue;
> spin_lock(&b->cache_lock);
> freed += prune_bucket(b);
> - if (!list_empty(&b->lru_head))
> - cancel = false;
> spin_unlock(&b->cache_lock);
> }
> -
> - /*
> - * Conditionally rearm the job to run in RC_EXPIRE since we just
> - * ran the pruner.
> - */
> - if (!cancel)
> - mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE);
> return freed;
> }
>
> -static void
> -cache_cleaner_func(struct work_struct *unused)
> -{
> - prune_cache_entries();
> -}
> -
> static unsigned long
> nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
> {
> --
> 2.4.3