Allocating an entire svc_rqst (including all of the pages, etc...) for
each workqueue request is pretty expensive. Keep a cache of allocated
svc_rqst structures for each NUMA node that we keep in svc_pool.
When an xprt needs servicing we look for an existing svc_rqst if
possible, attach the xprt to it and then queue it to do the work. If
one isn't currently available, we queue the svc_xprt work to allocate
one, add it to the cache and then queue the svc_rqst's work to handle
the rest.
In order to keep the cache from growing without bound, we register a
shrinker. Since the cache is already NUMA-aware, we can use a NUMA-aware
shrinker as well.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
---
fs/nfsd/nfssvc.c | 11 ++--
include/linux/sunrpc/svc.h | 11 ++++
net/sunrpc/svc.c | 1 +
net/sunrpc/svc_wq.c | 158 ++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 172 insertions(+), 9 deletions(-)
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 7e22068bdad4..416faf9a77f0 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -669,26 +669,25 @@ nfsd_rqst_work(struct work_struct *work)
rqstp->rq_server->sv_maxconn = nn->max_connections;
if (svc_wq_recv(rqstp) < 0) {
- svc_rqst_free(rqstp);
+ put_svc_rqst(rqstp);
return;
}
saved_fs = swap_fs_struct(rqstp->rq_fs);
svc_process(rqstp);
- saved_fs = swap_fs_struct(saved_fs);
- svc_rqst_free(rqstp);
+ swap_fs_struct(saved_fs);
+ put_svc_rqst(rqstp);
}
/* work function for workqueue-based nfsd */
static void
nfsd_xprt_work(struct work_struct *work)
{
- int node = numa_node_id();
struct svc_xprt *xprt = container_of(work, struct svc_xprt, xpt_work);
- struct svc_rqst *rqstp;
struct svc_serv *serv = xprt->xpt_server;
+ struct svc_rqst *rqstp;
- rqstp = svc_rqst_alloc(serv, &serv->sv_pools[node], node);
+ rqstp = find_or_alloc_svc_rqst(serv);
if (!rqstp) {
/* Alloc failure. Give up for now, and requeue the work */
queue_work(serv->sv_wq, &xprt->xpt_work);
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 695bc989c007..4a71436efb1f 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -108,6 +108,7 @@ struct svc_serv {
struct svc_pool * sv_pools; /* array of thread pools */
struct svc_serv_ops * sv_ops; /* server operations */
struct workqueue_struct *sv_wq; /* workqueue for wq-based services */
+ struct shrinker sv_shrinker; /* for shrinking svc_rqst caches */
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
struct list_head sv_cb_list; /* queue for callback requests
* that arrive over the same
@@ -277,6 +278,7 @@ struct svc_rqst {
#define RQ_VICTIM (5) /* about to be shut down */
#define RQ_BUSY (6) /* request is busy */
unsigned long rq_flags; /* flags field */
+ unsigned long rq_time; /* when rqstp was last put */
void * rq_argp; /* decoded arguments */
void * rq_resp; /* xdr'd results */
@@ -496,6 +498,15 @@ char * svc_print_addr(struct svc_rqst *, char *, size_t);
int svc_wq_setup(struct svc_serv *, struct svc_pool *, int);
void svc_wq_enqueue_xprt(struct svc_xprt *);
+struct svc_rqst * find_or_alloc_svc_rqst(struct svc_serv *serv);
+void exit_svc_rqst_cache(struct svc_serv *serv);
+
+static inline void
+put_svc_rqst(struct svc_rqst *rqstp)
+{
+ rqstp->rq_time = jiffies;
+ clear_bit(RQ_BUSY, &rqstp->rq_flags);
+}
#define RPC_MAX_ADDRBUFLEN (63U)
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 78395f790b54..32018951928e 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -545,6 +545,7 @@ svc_destroy(struct svc_serv *serv)
if (serv->sv_wq) {
destroy_workqueue(serv->sv_wq);
+ exit_svc_rqst_cache(serv);
module_put(serv->sv_ops->svo_module);
}
diff --git a/net/sunrpc/svc_wq.c b/net/sunrpc/svc_wq.c
index d1778373249e..1ca26d51b8ec 100644
--- a/net/sunrpc/svc_wq.c
+++ b/net/sunrpc/svc_wq.c
@@ -11,6 +11,143 @@
#include <linux/workqueue.h>
#include <trace/events/sunrpc.h>
+static struct svc_rqst *
+find_svc_rqst(struct svc_serv *serv)
+{
+ int node = numa_node_id();
+ struct svc_rqst *rqstp;
+ struct svc_pool *pool = &serv->sv_pools[node];
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
+ if (!test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) {
+ rcu_read_unlock();
+ return rqstp;
+ }
+ }
+ rcu_read_unlock();
+ return NULL;
+}
+
+/*
+ * Find a svc_rqst to use. Try to find an already allocated-one on the list
+ * first, and then allocate if there isn't one available.
+ */
+struct svc_rqst *
+find_or_alloc_svc_rqst(struct svc_serv *serv)
+{
+ int node = numa_node_id();
+ struct svc_rqst *rqstp;
+ struct svc_pool *pool = &serv->sv_pools[node];
+
+ rqstp = find_svc_rqst(serv);
+ if (likely(rqstp))
+ return rqstp;
+
+ rqstp = svc_rqst_alloc(serv, pool, node);
+ if (rqstp) {
+ spin_lock_bh(&pool->sp_lock);
+ list_add_tail_rcu(&rqstp->rq_all, &pool->sp_all_threads);
+ ++pool->sp_nrthreads;
+ spin_unlock_bh(&pool->sp_lock);
+ }
+ return rqstp;
+}
+EXPORT_SYMBOL_GPL(find_or_alloc_svc_rqst);
+
+static unsigned long
+count_svc_rqst_objects(struct shrinker *shrinker, struct shrink_control *sc)
+{
+ struct svc_serv *serv = container_of(shrinker, struct svc_serv,
+ sv_shrinker);
+ struct svc_pool *pool = &serv->sv_pools[sc->nid];
+ struct svc_rqst *rqstp;
+ unsigned long count = 0;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
+ /* Don't count it if it's busy */
+ if (test_bit(RQ_BUSY, &rqstp->rq_flags))
+ continue;
+
+ /* Don't count it if it was used within the last second */
+ if (time_before(jiffies, rqstp->rq_time + HZ))
+ continue;
+
+ ++count;
+ }
+ rcu_read_unlock();
+
+ return count;
+}
+
+static unsigned long
+scan_svc_rqst_objects(struct shrinker *shrinker, struct shrink_control *sc)
+{
+ struct svc_serv *serv = container_of(shrinker, struct svc_serv,
+ sv_shrinker);
+ struct svc_pool *pool = &serv->sv_pools[sc->nid];
+ struct svc_rqst *rqstp;
+ unsigned long count = 0;
+
+ spin_lock(&pool->sp_lock);
+ list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
+ /* Don't free it if it's busy */
+ if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags))
+ continue;
+
+ list_del_rcu(&rqstp->rq_all);
+ svc_rqst_free(rqstp);
+ --pool->sp_nrthreads;
+ ++count;
+ if (sc->nr_to_scan-- == 0)
+ break;
+ }
+ spin_unlock(&pool->sp_lock);
+
+ return count;
+}
+
+static int
+init_svc_rqst_cache(struct svc_serv *serv)
+{
+ struct shrinker *shrinker = &serv->sv_shrinker;
+
+ memset(shrinker, 0, sizeof(*shrinker));
+
+ shrinker->count_objects = count_svc_rqst_objects;
+ shrinker->scan_objects = scan_svc_rqst_objects;
+ shrinker->seeks = DEFAULT_SEEKS;
+ shrinker->flags = SHRINKER_NUMA_AWARE;
+
+ return register_shrinker(shrinker);
+}
+
+void
+exit_svc_rqst_cache(struct svc_serv *serv)
+{
+ int node;
+
+ unregister_shrinker(&serv->sv_shrinker);
+
+ for (node = 0; node < serv->sv_nrpools; node++) {
+ struct svc_pool *pool = &serv->sv_pools[node];
+
+ spin_lock_bh(&pool->sp_lock);
+ while (!list_empty(&pool->sp_all_threads)) {
+ struct svc_rqst *rqstp = list_first_entry(
+ &pool->sp_all_threads, struct svc_rqst,
+ rq_all);
+
+ WARN_ON_ONCE(test_bit(RQ_BUSY, &rqstp->rq_flags));
+ list_del_rcu(&rqstp->rq_all);
+ svc_rqst_free(rqstp);
+ }
+ pool->sp_nrthreads = 0;
+ spin_unlock_bh(&pool->sp_lock);
+ }
+}
+
/*
* This workqueue job should run on each node when the workqueue is created. It
* walks the list of xprts for its node, and queues the workqueue job for each.
@@ -58,8 +195,8 @@ process_queued_xprts(struct svc_serv *serv)
/*
* Start up or shut down a workqueue-based RPC service. Basically, we use this
- * to allocate the workqueue. The function assumes that the caller holds one
- * serv->sv_nrthreads reference.
+ * to allocate the workqueue and set up the shrinker for the svc_rqst cache.
+ * This function assumes that the caller holds one serv->sv_nrthreads reference.
*
* The "active" parm is treated as a boolean here. The only meaningful values
* are non-zero which means that we're starting the service up, or zero which
@@ -68,6 +205,7 @@ process_queued_xprts(struct svc_serv *serv)
int
svc_wq_setup(struct svc_serv *serv, struct svc_pool *pool, int active)
{
+ int err;
int nrthreads = serv->sv_nrthreads - 1; /* -1 for caller's reference */
WARN_ON_ONCE(nrthreads < 0);
@@ -85,14 +223,20 @@ svc_wq_setup(struct svc_serv *serv, struct svc_pool *pool, int active)
* down the workqueue until the closing of the xprts is done.
*/
if (!nrthreads && active) {
+ err = init_svc_rqst_cache(serv);
+ if (err)
+ return err;
+
__module_get(serv->sv_ops->svo_module);
serv->sv_wq = alloc_workqueue("%s",
WQ_UNBOUND|WQ_FREEZABLE|WQ_SYSFS,
0, serv->sv_name);
if (!serv->sv_wq) {
+ exit_svc_rqst_cache(serv);
module_put(serv->sv_ops->svo_module);
return -ENOMEM;
}
+
process_queued_xprts(serv);
}
@@ -111,6 +255,7 @@ void
svc_wq_enqueue_xprt(struct svc_xprt *xprt)
{
struct svc_serv *serv = xprt->xpt_server;
+ struct svc_rqst *rqstp;
if (!svc_xprt_has_something_to_do(xprt))
return;
@@ -139,8 +284,15 @@ svc_wq_enqueue_xprt(struct svc_xprt *xprt)
spin_unlock_bh(&pool->sp_lock);
return;
}
+
out:
svc_xprt_get(xprt);
- queue_work(serv->sv_wq, &xprt->xpt_work);
+ rqstp = find_svc_rqst(serv);
+ if (!rqstp) {
+ queue_work(serv->sv_wq, &xprt->xpt_work);
+ return;
+ }
+ rqstp->rq_xprt = xprt;
+ queue_work(serv->sv_wq, &rqstp->rq_work);
}
EXPORT_SYMBOL_GPL(svc_wq_enqueue_xprt);
--
2.1.0
--
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