[RFC PATCH 09/14] sunrpc: add basic support for workqueue-based services
From: Jeff Layton
Date: Tue Dec 02 2014 - 13:26:28 EST
Add a new "workqueue" pool mode setting. When that is configured, we'll
set up a svc_pool for each NUMA node, but don't bother with the
pool <=> cpu mapping arrays.
We use an unbound workqueue, which should naturally make each xprt be
queued to a CPU within the current NUMA node.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
---
include/linux/sunrpc/svc.h | 10 ++-
include/linux/sunrpc/svc_xprt.h | 1 +
include/linux/sunrpc/svcsock.h | 1 +
net/sunrpc/Kconfig | 10 +++
net/sunrpc/Makefile | 1 +
net/sunrpc/svc.c | 15 ++++
net/sunrpc/svc_wq.c | 148 ++++++++++++++++++++++++++++++++++++++++
net/sunrpc/svc_xprt.c | 49 ++++++++++++-
8 files changed, 233 insertions(+), 2 deletions(-)
create mode 100644 net/sunrpc/svc_wq.c
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 8bd53f723485..81e723220346 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -47,6 +47,7 @@ struct svc_pool {
#define SP_TASK_PENDING (0) /* still work to do even if no
* xprt is queued. */
unsigned long sp_flags;
+ struct work_struct sp_work; /* per-pool work struct */
} ____cacheline_aligned_in_smp;
struct svc_serv;
@@ -103,6 +104,7 @@ struct svc_serv {
unsigned int sv_nrpools; /* number of thread pools */
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 */
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
struct list_head sv_cb_list; /* queue for callback requests
* that arrive over the same
@@ -438,7 +440,8 @@ enum {
SVC_POOL_GLOBAL, /* no mapping, just a single global pool
* (legacy & UP mode) */
SVC_POOL_PERCPU, /* one pool per cpu */
- SVC_POOL_PERNODE /* one pool per numa node */
+ SVC_POOL_PERNODE, /* one pool per numa node */
+ SVC_POOL_WORKQUEUE, /* workqueue-based service */
};
struct svc_pool_map {
@@ -486,6 +489,11 @@ void svc_reserve(struct svc_rqst *rqstp, int space);
struct svc_pool * svc_pool_for_cpu(struct svc_serv *serv, int cpu);
char * svc_print_addr(struct svc_rqst *, char *, size_t);
+#if IS_ENABLED(CONFIG_SUNRPC_SVC_WORKQUEUE)
+int svc_wq_setup(struct svc_serv *, struct svc_pool *, int);
+void svc_wq_enqueue_xprt(struct svc_xprt *);
+#endif
+
#define RPC_MAX_ADDRBUFLEN (63U)
/*
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 096937871cda..ce7fd68a905e 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -117,6 +117,7 @@ void svc_xprt_init(struct net *, struct svc_xprt_class *, struct svc_xprt *,
struct svc_serv *);
int svc_create_xprt(struct svc_serv *, const char *, struct net *,
const int, const unsigned short, int);
+bool svc_xprt_has_something_to_do(struct svc_xprt *xprt);
void svc_xprt_do_enqueue(struct svc_xprt *xprt);
void svc_xprt_enqueue(struct svc_xprt *xprt);
void svc_xprt_put(struct svc_xprt *xprt);
diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index 2e780134f449..3ce0a640605d 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -53,6 +53,7 @@ static inline u32 svc_sock_final_rec(struct svc_sock *svsk)
*/
void svc_close_net(struct svc_serv *, struct net *);
int svc_recv(struct svc_rqst *, long);
+int svc_wq_recv(struct svc_rqst *);
int svc_send(struct svc_rqst *);
void svc_drop(struct svc_rqst *);
void svc_sock_update_bufs(struct svc_serv *serv);
diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
index fb78117b896c..08e01949bdc5 100644
--- a/net/sunrpc/Kconfig
+++ b/net/sunrpc/Kconfig
@@ -71,3 +71,13 @@ config SUNRPC_XPRT_RDMA_SERVER
choose M here: the module will be called svcrdma.
If unsure, say N.
+
+config SUNRPC_SVC_WORKQUEUE
+ bool "Support for workqueue-based SUNRPC services"
+ depends on SUNRPC
+ default n
+ help
+ Traditional SUNRPC services have required a dedicated thread
+ to handle incoming requests. This option enables support for
+ queueing incoming reqests to a workqueue instead, eliminating
+ the need for a dedicated thread pool.
diff --git a/net/sunrpc/Makefile b/net/sunrpc/Makefile
index 15e6f6c23c5d..401341123fdd 100644
--- a/net/sunrpc/Makefile
+++ b/net/sunrpc/Makefile
@@ -18,3 +18,4 @@ sunrpc-$(CONFIG_SUNRPC_DEBUG) += debugfs.o
sunrpc-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel_rqst.o bc_svc.o
sunrpc-$(CONFIG_PROC_FS) += stats.o
sunrpc-$(CONFIG_SYSCTL) += sysctl.o
+sunrpc-$(CONFIG_SUNRPC_SVC_WORKQUEUE) += svc_wq.o
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 135ffbe9d983..7c8e33923210 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -71,6 +71,10 @@ param_set_pool_mode(const char *val, struct kernel_param *kp)
*ip = SVC_POOL_PERCPU;
else if (!strncmp(val, "pernode", 7))
*ip = SVC_POOL_PERNODE;
+#if IS_ENABLED(CONFIG_SUNRPC_SVC_WORKQUEUE)
+ else if (!strncmp(val, "workqueue", 9))
+ *ip = SVC_POOL_WORKQUEUE;
+#endif
else
err = -EINVAL;
@@ -94,6 +98,8 @@ param_get_pool_mode(char *buf, struct kernel_param *kp)
return strlcpy(buf, "percpu", 20);
case SVC_POOL_PERNODE:
return strlcpy(buf, "pernode", 20);
+ case SVC_POOL_WORKQUEUE:
+ return strlcpy(buf, "workqueue", 20);
default:
return sprintf(buf, "%d", *ip);
}
@@ -242,6 +248,10 @@ svc_pool_map_get(void)
case SVC_POOL_PERNODE:
npools = svc_pool_map_init_pernode(m);
break;
+ case SVC_POOL_WORKQUEUE:
+ /* workqueues get a pool per numa node, but don't need a map */
+ npools = nr_node_ids;
+ break;
}
if (npools < 0) {
@@ -534,6 +544,11 @@ svc_destroy(struct svc_serv *serv)
if (svc_serv_is_pooled(serv))
svc_pool_map_put();
+ if (serv->sv_wq) {
+ destroy_workqueue(serv->sv_wq);
+ module_put(serv->sv_ops->svo_module);
+ }
+
kfree(serv->sv_pools);
kfree(serv);
}
diff --git a/net/sunrpc/svc_wq.c b/net/sunrpc/svc_wq.c
new file mode 100644
index 000000000000..d4720ecd0b32
--- /dev/null
+++ b/net/sunrpc/svc_wq.c
@@ -0,0 +1,148 @@
+/*
+ * svc_wq - support for workqueue-based rpc svcs
+ */
+
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/sunrpc/stats.h>
+#include <linux/sunrpc/svc_xprt.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <trace/events/sunrpc.h>
+
+/*
+ * 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.
+ */
+static void
+process_queued_xprt_work(struct work_struct *work)
+{
+ struct svc_pool *pool = container_of(work, struct svc_pool, sp_work);
+
+ spin_lock_bh(&pool->sp_lock);
+ while (!list_empty(&pool->sp_sockets)) {
+ struct svc_xprt *xprt = list_first_entry(&pool->sp_sockets,
+ struct svc_xprt, xpt_ready);
+
+ list_del_init(&xprt->xpt_ready);
+ svc_xprt_get(xprt);
+ queue_work(xprt->xpt_server->sv_wq, &xprt->xpt_work);
+ }
+ spin_unlock_bh(&pool->sp_lock);
+}
+
+/*
+ * If any svc_xprts are enqueued before the workqueue is available, they get
+ * added to the pool->sp_sockets list. When the workqueue becomes available,
+ * we must walk the list for each pool and queue each xprt to the workqueue.
+ *
+ * In order to minimize inter-node communication, we queue a separate job for
+ * each node to walk its own list. We queue this job to any cpu in the node.
+ * Since the workqueues are unbound they'll end up queued to the pool_workqueue
+ * for their corresponding node, and not necessarily to the given CPU.
+ */
+static void
+process_queued_xprts(struct svc_serv *serv)
+{
+ int node;
+
+ for (node = 0; node < serv->sv_nrpools; ++node) {
+ int cpu = any_online_cpu(*cpumask_of_node(node));
+ struct svc_pool *pool = &serv->sv_pools[node];
+
+ INIT_WORK(&pool->sp_work, process_queued_xprt_work);
+ queue_work_on(cpu, serv->sv_wq, &pool->sp_work);
+ }
+}
+
+/*
+ * 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.
+ */
+int
+svc_wq_setup(struct svc_serv *serv, struct svc_pool *pool, int max_active)
+{
+ int nrthreads = serv->sv_nrthreads - 1; /* -1 for caller's reference */
+
+ WARN_ON_ONCE(nrthreads < 0);
+
+ /*
+ * We don't allow tuning max_active on a per-node basis. If we got here
+ * via the pool_threads interface, then just return an error.
+ */
+ if (pool)
+ return -EINVAL;
+
+ if (!nrthreads) {
+ /* svc is down and none requested? */
+ if (!max_active)
+ return 0;
+ __module_get(serv->sv_ops->svo_module);
+ serv->sv_wq = alloc_workqueue("%s",
+ WQ_UNBOUND|WQ_FREEZABLE|WQ_SYSFS,
+ max_active, serv->sv_name);
+ if (!serv->sv_wq) {
+ module_put(serv->sv_ops->svo_module);
+ return -ENOMEM;
+ }
+ process_queued_xprts(serv);
+ } else {
+ /*
+ * If max_active is 0, then that means we're taking the service
+ * down. Don't destroy the workqueue just yet, as we need it
+ * to process the closing of the xprts.
+ */
+ if (max_active)
+ workqueue_set_max_active(serv->sv_wq, max_active);
+ }
+
+ /* +1 for caller's reference */
+ serv->sv_nrthreads = max_active + 1;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(svc_wq_setup);
+
+/*
+ * A svc_xprt needs to be serviced. Queue its workqueue job and return. In the
+ * event that the workqueue isn't available yet, add it to the sp_sockets list
+ * so that it can be processed when it does become available.
+ */
+void
+svc_wq_enqueue_xprt(struct svc_xprt *xprt)
+{
+ struct svc_serv *serv = xprt->xpt_server;
+
+ if (!svc_xprt_has_something_to_do(xprt))
+ return;
+
+ /* Don't enqueue transport while already enqueued */
+ if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
+ return;
+
+ /* No workqueue yet? Queue the socket until there is one. */
+ if (!serv->sv_wq) {
+ struct svc_pool *pool = &serv->sv_pools[numa_node_id()];
+
+ spin_lock_bh(&pool->sp_lock);
+
+ /*
+ * It's possible for the workqueue to be started up between
+ * when we checked for it before but before we took the lock.
+ * Check again while holding lock to avoid that potential race.
+ */
+ if (serv->sv_wq) {
+ spin_unlock_bh(&pool->sp_lock);
+ goto out;
+ }
+
+ list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
+ spin_unlock_bh(&pool->sp_lock);
+ return;
+ }
+out:
+ svc_xprt_get(xprt);
+ queue_work(serv->sv_wq, &xprt->xpt_work);
+}
+EXPORT_SYMBOL_GPL(svc_wq_enqueue_xprt);
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 63b42a8578c0..30f9fdfbff0c 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -313,7 +313,7 @@ char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
}
EXPORT_SYMBOL_GPL(svc_print_addr);
-static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
+bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
{
if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
return true;
@@ -850,6 +850,53 @@ out:
}
EXPORT_SYMBOL_GPL(svc_recv);
+#if IS_ENABLED(CONFIG_SUNRPC_SVC_WORKQUEUE)
+/*
+ * Perform a receive off the rqstp->rq_xprt socket.
+ *
+ * This function is a bit different from the standard svc_recv function as it
+ * assumes that the xprt is already provided in rqstp->rq_xprt, and so it
+ * does not sleep when there is no more work to be done.
+ */
+int
+svc_wq_recv(struct svc_rqst *rqstp)
+{
+ int len, err;
+ struct svc_xprt *xprt = rqstp->rq_xprt;
+ struct svc_serv *serv = xprt->xpt_server;
+
+ err = svc_alloc_arg(rqstp);
+ if (err)
+ goto out;
+
+ len = svc_handle_xprt(rqstp, xprt);
+ if (len <= 0) {
+ err = -EAGAIN;
+ goto out_release;
+ }
+
+ clear_bit(XPT_OLD, &xprt->xpt_flags);
+
+ if (xprt->xpt_ops->xpo_secure_port(rqstp))
+ set_bit(RQ_SECURE, &rqstp->rq_flags);
+ else
+ clear_bit(RQ_SECURE, &rqstp->rq_flags);
+ rqstp->rq_chandle.defer = svc_defer;
+ rqstp->rq_xid = svc_getu32(&rqstp->rq_arg.head[0]);
+
+ if (serv->sv_stats)
+ serv->sv_stats->netcnt++;
+ trace_svc_recv(rqstp, len);
+ return len;
+out_release:
+ rqstp->rq_res.len = 0;
+ svc_xprt_release(rqstp);
+out:
+ return err;
+}
+EXPORT_SYMBOL_GPL(svc_wq_recv);
+#endif
+
/*
* Drop request
*/
--
2.1.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/