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sunrpc: change sp_nrthreads from atomic_t to unsigned int.

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sp_nrthreads is only ever accessed under the service mutex
  nlmsvc_mutex nfs_callback_mutex nfsd_mutex
so these is no need for it to be an atomic_t.

The fact that all code using it is single-threaded means that we can
simplify svc_pool_victim and remove the temporary elevation of
sp_nrthreads.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
NeilBrown 2024-07-15 17:14:18 +10:00 committed by Chuck Lever
parent 16ef80eedc
commit 60749cbe3d
4 changed files with 15 additions and 24 deletions
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2
fs/nfsd/nfsctl.c
View File

@ -1769,7 +1769,7 @@ int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *info)
struct svc_pool *sp = &nn->nfsd_serv->sv_pools[i];
err = nla_put_u32(skb, NFSD_A_SERVER_THREADS,
atomic_read(&sp->sp_nrthreads));
sp->sp_nrthreads);
if (err)
goto err_unlock;
}

2
fs/nfsd/nfssvc.c
View File

@ -641,7 +641,7 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
if (serv)
for (i = 0; i < serv->sv_nrpools && i < n; i++)
nthreads[i] = atomic_read(&serv->sv_pools[i].sp_nrthreads);
nthreads[i] = serv->sv_pools[i].sp_nrthreads;
return 0;
}

4
include/linux/sunrpc/svc.h
View File

@ -33,9 +33,9 @@
* node traffic on multi-node NUMA NFS servers.
*/
struct svc_pool {
unsigned int sp_id; /* pool id; also node id on NUMA */
unsigned int sp_id; /* pool id; also node id on NUMA */
struct lwq sp_xprts; /* pending transports */
atomic_t sp_nrthreads; /* # of threads in pool */
unsigned int sp_nrthreads; /* # of threads in pool */
struct list_head sp_all_threads; /* all server threads */
struct llist_head sp_idle_threads; /* idle server threads */

31
net/sunrpc/svc.c
View File

@ -725,7 +725,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
serv->sv_nrthreads += 1;
spin_unlock_bh(&serv->sv_lock);
atomic_inc(&pool->sp_nrthreads);
pool->sp_nrthreads += 1;
/* Protected by whatever lock the service uses when calling
* svc_set_num_threads()
@ -780,31 +780,22 @@ svc_pool_victim(struct svc_serv *serv, struct svc_pool *target_pool,
struct svc_pool *pool;
unsigned int i;
retry:
pool = target_pool;
if (pool != NULL) {
if (atomic_inc_not_zero(&pool->sp_nrthreads))
goto found_pool;
return NULL;
} else {
if (!pool) {
for (i = 0; i < serv->sv_nrpools; i++) {
pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
if (atomic_inc_not_zero(&pool->sp_nrthreads))
goto found_pool;
if (pool->sp_nrthreads)
break;
}
return NULL;
}
found_pool:
set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
set_bit(SP_NEED_VICTIM, &pool->sp_flags);
if (!atomic_dec_and_test(&pool->sp_nrthreads))
if (pool && pool->sp_nrthreads) {
set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
set_bit(SP_NEED_VICTIM, &pool->sp_flags);
return pool;
/* Nothing left in this pool any more */
clear_bit(SP_NEED_VICTIM, &pool->sp_flags);
clear_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
goto retry;
}
return NULL;
}
static int
@ -883,7 +874,7 @@ svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
if (!pool)
nrservs -= serv->sv_nrthreads;
else
nrservs -= atomic_read(&pool->sp_nrthreads);
nrservs -= pool->sp_nrthreads;
if (nrservs > 0)
return svc_start_kthreads(serv, pool, nrservs);
@ -967,7 +958,7 @@ svc_exit_thread(struct svc_rqst *rqstp)
list_del_rcu(&rqstp->rq_all);
atomic_dec(&pool->sp_nrthreads);
pool->sp_nrthreads -= 1;
spin_lock_bh(&serv->sv_lock);
serv->sv_nrthreads -= 1;