[PATCH 008 of 11] knfsd: add svc_set_num_threads
From: NeilBrown
Date: Sun Jul 30 2006 - 20:42:30 EST
From: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>
knfsd: Currently knfsd keeps its own list of all nfsd threads
in nfssvc.c; add a new way of managing the list of all threads
in a svc_serv. Add svc_create_pooled() to allow creation of
a svc_serv whose threads are managed by the sunrpc code. Add
svc_set_num_threads() to manage the number of threads in a service,
either per-pool or globally across the service.
Signed-off-by: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
### Diffstat output
./include/linux/sunrpc/svc.h | 21 ++++--
./net/sunrpc/sunrpc_syms.c | 2
./net/sunrpc/svc.c | 139 ++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 154 insertions(+), 8 deletions(-)
diff .prev/include/linux/sunrpc/svc.h ./include/linux/sunrpc/svc.h
--- .prev/include/linux/sunrpc/svc.h 2006-07-31 10:29:38.000000000 +1000
+++ ./include/linux/sunrpc/svc.h 2006-07-31 10:30:30.000000000 +1000
@@ -17,6 +17,10 @@
#include <linux/wait.h>
#include <linux/mm.h>
+/*
+ * This is the RPC server thread function prototype
+ */
+typedef void (*svc_thread_fn)(struct svc_rqst *);
/*
*
@@ -34,6 +38,7 @@ struct svc_pool {
struct list_head sp_threads; /* idle server threads */
struct list_head sp_sockets; /* pending sockets */
unsigned int sp_nrthreads; /* # of threads in pool */
+ struct list_head sp_all_threads; /* all server threads */
} ____cacheline_aligned_in_smp;
/*
@@ -68,6 +73,11 @@ struct svc_serv {
/* Callback to use when last thread
* exits.
*/
+
+ struct module * sv_module; /* optional module to count when
+ * adding threads */
+ svc_thread_fn sv_function; /* main function for threads */
+ int sv_kill_signal; /* signal to kill threads */
};
/*
@@ -147,6 +157,7 @@ static inline void svc_putu32(struct kve
*/
struct svc_rqst {
struct list_head rq_list; /* idle list */
+ struct list_head rq_all; /* all threads list */
struct svc_sock * rq_sock; /* socket */
struct sockaddr_in rq_addr; /* peer address */
int rq_addrlen;
@@ -201,6 +212,7 @@ struct svc_rqst {
* to prevent encrypting page
* cache pages */
wait_queue_head_t rq_wait; /* synchronization */
+ struct task_struct *rq_task; /* service thread */
};
/*
@@ -342,17 +354,16 @@ struct svc_procedure {
};
/*
- * This is the RPC server thread function prototype
- */
-typedef void (*svc_thread_fn)(struct svc_rqst *);
-
-/*
* Function prototypes.
*/
struct svc_serv * svc_create(struct svc_program *, unsigned int,
void (*shutdown)(struct svc_serv*));
int svc_create_thread(svc_thread_fn, struct svc_serv *);
void svc_exit_thread(struct svc_rqst *);
+struct svc_serv * svc_create_pooled(struct svc_program *, unsigned int,
+ void (*shutdown)(struct svc_serv*),
+ svc_thread_fn, int sig, struct module *);
+int svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
void svc_destroy(struct svc_serv *);
int svc_process(struct svc_rqst *);
int svc_register(struct svc_serv *, int, unsigned short);
diff .prev/net/sunrpc/sunrpc_syms.c ./net/sunrpc/sunrpc_syms.c
--- .prev/net/sunrpc/sunrpc_syms.c 2006-07-31 10:29:38.000000000 +1000
+++ ./net/sunrpc/sunrpc_syms.c 2006-07-31 10:30:30.000000000 +1000
@@ -73,6 +73,8 @@ EXPORT_SYMBOL(put_rpccred);
/* RPC server stuff */
EXPORT_SYMBOL(svc_create);
EXPORT_SYMBOL(svc_create_thread);
+EXPORT_SYMBOL(svc_create_pooled);
+EXPORT_SYMBOL(svc_set_num_threads);
EXPORT_SYMBOL(svc_exit_thread);
EXPORT_SYMBOL(svc_destroy);
EXPORT_SYMBOL(svc_drop);
diff .prev/net/sunrpc/svc.c ./net/sunrpc/svc.c
--- .prev/net/sunrpc/svc.c 2006-07-31 10:29:38.000000000 +1000
+++ ./net/sunrpc/svc.c 2006-07-31 10:30:30.000000000 +1000
@@ -12,6 +12,8 @@
#include <linux/net.h>
#include <linux/in.h>
#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
@@ -25,8 +27,8 @@
/*
* Create an RPC service
*/
-struct svc_serv *
-svc_create(struct svc_program *prog, unsigned int bufsize,
+static struct svc_serv *
+__svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
void (*shutdown)(struct svc_serv *serv))
{
struct svc_serv *serv;
@@ -61,7 +63,7 @@ svc_create(struct svc_program *prog, uns
init_timer(&serv->sv_temptimer);
spin_lock_init(&serv->sv_lock);
- serv->sv_nrpools = 1;
+ serv->sv_nrpools = npools;
serv->sv_pools =
kcalloc(sizeof(struct svc_pool), serv->sv_nrpools,
GFP_KERNEL);
@@ -79,6 +81,7 @@ svc_create(struct svc_program *prog, uns
pool->sp_id = i;
INIT_LIST_HEAD(&pool->sp_threads);
INIT_LIST_HEAD(&pool->sp_sockets);
+ INIT_LIST_HEAD(&pool->sp_all_threads);
spin_lock_init(&pool->sp_lock);
}
@@ -89,6 +92,31 @@ svc_create(struct svc_program *prog, uns
return serv;
}
+struct svc_serv *
+svc_create(struct svc_program *prog, unsigned int bufsize,
+ void (*shutdown)(struct svc_serv *serv))
+{
+ return __svc_create(prog, bufsize, /*npools*/1, shutdown);
+}
+
+struct svc_serv *
+svc_create_pooled(struct svc_program *prog, unsigned int bufsize,
+ void (*shutdown)(struct svc_serv *serv),
+ svc_thread_fn func, int sig, struct module *mod)
+{
+ struct svc_serv *serv;
+
+ serv = __svc_create(prog, bufsize, /*npools*/1, shutdown);
+
+ if (serv != NULL) {
+ serv->sv_function = func;
+ serv->sv_kill_signal = sig;
+ serv->sv_module = mod;
+ }
+
+ return serv;
+}
+
/*
* Destroy an RPC service. Should be called with the BKL held
*/
@@ -203,6 +231,7 @@ __svc_create_thread(svc_thread_fn func,
serv->sv_nrthreads++;
spin_lock_bh(&pool->sp_lock);
pool->sp_nrthreads++;
+ list_add(&rqstp->rq_all, &pool->sp_all_threads);
spin_unlock_bh(&pool->sp_lock);
rqstp->rq_server = serv;
rqstp->rq_pool = pool;
@@ -229,6 +258,109 @@ svc_create_thread(svc_thread_fn func, st
}
/*
+ * Choose a pool in which to create a new thread, for svc_set_num_threads
+ */
+static inline struct svc_pool *
+choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
+{
+ if (pool != NULL)
+ return pool;
+
+ return &serv->sv_pools[(*state)++ % serv->sv_nrpools];
+}
+
+/*
+ * Choose a thread to kill, for svc_set_num_threads
+ */
+static inline struct task_struct *
+choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
+{
+ unsigned int i;
+ struct task_struct *task = NULL;
+
+ if (pool != NULL) {
+ spin_lock_bh(&pool->sp_lock);
+ } else {
+ /* choose a pool in round-robin fashion */
+ for (i = 0 ; i < serv->sv_nrpools ; i++) {
+ pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
+ spin_lock_bh(&pool->sp_lock);
+ if (!list_empty(&pool->sp_all_threads))
+ goto found_pool;
+ spin_unlock_bh(&pool->sp_lock);
+ }
+ return NULL;
+ }
+
+found_pool:
+ if (!list_empty(&pool->sp_all_threads)) {
+ struct svc_rqst *rqstp;
+
+ /*
+ * Remove from the pool->sp_all_threads list
+ * so we don't try to kill it again.
+ */
+ rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all);
+ list_del_init(&rqstp->rq_all);
+ task = rqstp->rq_task;
+ }
+ spin_unlock_bh(&pool->sp_lock);
+
+ return task;
+}
+
+/*
+ * Create or destroy enough new threads to make the number
+ * of threads the given number. If `pool' is non-NULL, applies
+ * only to threads in that pool, otherwise round-robins between
+ * all pools. Must be called with a svc_get() reference and
+ * the BKL held.
+ *
+ * Destroying threads relies on the service threads filling in
+ * rqstp->rq_task, which only the nfs ones do. Assumes the serv
+ * has been created using svc_create_pooled().
+ *
+ * Based on code that used to be in nfsd_svc() but tweaked
+ * to be pool-aware.
+ */
+int
+svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
+{
+ struct task_struct *victim;
+ int error = 0;
+ unsigned int state = serv->sv_nrthreads-1;
+
+ if (pool == NULL) {
+ /* The -1 assumes caller has done a svc_get() */
+ nrservs -= (serv->sv_nrthreads-1);
+ } else {
+ spin_lock_bh(&pool->sp_lock);
+ nrservs -= pool->sp_nrthreads;
+ spin_unlock_bh(&pool->sp_lock);
+ }
+
+ /* create new threads */
+ while (nrservs > 0) {
+ nrservs--;
+ __module_get(serv->sv_module);
+ error = __svc_create_thread(serv->sv_function, serv,
+ choose_pool(serv, pool, &state));
+ if (error < 0) {
+ module_put(serv->sv_module);
+ break;
+ }
+ }
+ /* destroy old threads */
+ while (nrservs < 0 &&
+ (victim = choose_victim(serv, pool, &state)) != NULL) {
+ send_sig(serv->sv_kill_signal, victim, 1);
+ nrservs++;
+ }
+
+ return error;
+}
+
+/*
* Called from a server thread as it's exiting. Caller must hold BKL.
*/
void
@@ -244,6 +376,7 @@ svc_exit_thread(struct svc_rqst *rqstp)
spin_lock_bh(&pool->sp_lock);
pool->sp_nrthreads--;
+ list_del(&rqstp->rq_all);
spin_unlock_bh(&pool->sp_lock);
kfree(rqstp);
-
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