Commit a7455442 authored by Greg Banks's avatar Greg Banks Committed by Linus Torvalds
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[PATCH] knfsd: add svc_set_num_threads



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: default avatarGreg Banks <gnb@melbourne.sgi.com>
Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 9a24ab57
......@@ -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 */
};
/*
......@@ -164,6 +174,7 @@ static inline void svc_putu32(struct kvec *iov, __be32 val)
*/
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;
......@@ -218,6 +229,7 @@ struct svc_rqst {
* to prevent encrypting page
* cache pages */
wait_queue_head_t rq_wait; /* synchronization */
struct task_struct *rq_task; /* service thread */
};
/*
......@@ -358,11 +370,6 @@ struct svc_procedure {
unsigned int pc_xdrressize; /* maximum size of XDR reply */
};
/*
* This is the RPC server thread function prototype
*/
typedef void (*svc_thread_fn)(struct svc_rqst *);
/*
* Function prototypes.
*/
......@@ -370,6 +377,10 @@ 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);
......
......@@ -70,6 +70,8 @@ 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);
......
......@@ -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, unsigned int bufsize,
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, unsigned int bufsize,
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, unsigned int bufsize,
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, struct svc_serv *serv,
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;
......@@ -228,6 +257,109 @@ svc_create_thread(svc_thread_fn func, struct svc_serv *serv)
return __svc_create_thread(func, serv, &serv->sv_pools[0]);
}
/*
* 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.
*/
......@@ -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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