From 7ffc7ade2cb1138ea5d4ab55cb42c878d44165fb Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 6 Jan 2026 13:59:46 -0500 Subject: [PATCH] sunrpc: introduce the concept of a minimum number of threads per pool Add a new pool->sp_nrthrmin field to track the minimum number of threads in a pool. Add min_threads parameters to both svc_set_num_threads() and svc_set_pool_threads(). If min_threads is non-zero and less than the max, svc_set_num_threads() will ensure that the number of running threads is between the min and the max. If the min is 0 or greater than the max, then it is ignored, and the maximum number of threads will be started, and never spun down. For now, the min_threads is always 0, but a later patch will pass the proper value through from nfsd. Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever --- fs/lockd/svc.c | 4 ++-- fs/nfs/callback.c | 8 +++---- fs/nfsd/nfssvc.c | 8 +++---- include/linux/sunrpc/svc.h | 8 ++++--- net/sunrpc/svc.c | 45 +++++++++++++++++++++++++++++++------- 5 files changed, 52 insertions(+), 21 deletions(-) diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index fbf132b4e08d1..e2a1b12272f56 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -340,7 +340,7 @@ static int lockd_get(void) return -ENOMEM; } - error = svc_set_num_threads(serv, 1); + error = svc_set_num_threads(serv, 0, 1); if (error < 0) { svc_destroy(&serv); return error; @@ -368,7 +368,7 @@ static void lockd_put(void) unregister_inet6addr_notifier(&lockd_inet6addr_notifier); #endif - svc_set_num_threads(nlmsvc_serv, 0); + svc_set_num_threads(nlmsvc_serv, 0, 0); timer_delete_sync(&nlmsvc_retry); svc_destroy(&nlmsvc_serv); dprintk("lockd_down: service destroyed\n"); diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index d01de143927bf..6889818138e3a 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -119,9 +119,9 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt, if (serv->sv_nrthreads == nrservs) return 0; - ret = svc_set_num_threads(serv, nrservs); + ret = svc_set_num_threads(serv, 0, nrservs); if (ret) { - svc_set_num_threads(serv, 0); + svc_set_num_threads(serv, 0, 0); return ret; } dprintk("nfs_callback_up: service started\n"); @@ -242,7 +242,7 @@ int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt) cb_info->users++; err_net: if (!cb_info->users) { - svc_set_num_threads(cb_info->serv, 0); + svc_set_num_threads(cb_info->serv, 0, 0); svc_destroy(&cb_info->serv); } err_create: @@ -268,7 +268,7 @@ void nfs_callback_down(int minorversion, struct net *net, struct rpc_xprt *xprt) nfs_callback_down_net(minorversion, serv, net); cb_info->users--; if (cb_info->users == 0) { - svc_set_num_threads(serv, 0); + svc_set_num_threads(serv, 0, 0); dprintk("nfs_callback_down: service destroyed\n"); xprt_svc_destroy_nullify_bc(xprt, &cb_info->serv); } diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 049165ee26afc..1b3a143e0b296 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -580,7 +580,7 @@ void nfsd_shutdown_threads(struct net *net) } /* Kill outstanding nfsd threads */ - svc_set_num_threads(serv, 0); + svc_set_num_threads(serv, 0, 0); nfsd_destroy_serv(net); mutex_unlock(&nfsd_mutex); } @@ -690,7 +690,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) /* Special case: When n == 1, distribute threads equally among pools. */ if (n == 1) - return svc_set_num_threads(nn->nfsd_serv, nthreads[0]); + return svc_set_num_threads(nn->nfsd_serv, 0, nthreads[0]); if (n > nn->nfsd_serv->sv_nrpools) n = nn->nfsd_serv->sv_nrpools; @@ -718,7 +718,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) for (i = 0; i < n; i++) { err = svc_set_pool_threads(nn->nfsd_serv, &nn->nfsd_serv->sv_pools[i], - nthreads[i]); + 0, nthreads[i]); if (err) goto out; } @@ -727,7 +727,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) for (i = n; i < nn->nfsd_serv->sv_nrpools; ++i) { err = svc_set_pool_threads(nn->nfsd_serv, &nn->nfsd_serv->sv_pools[i], - 0); + 0, 0); if (err) goto out; } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index ec2b6ef548235..8fd511d02f3b3 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -36,6 +36,7 @@ struct svc_pool { unsigned int sp_id; /* pool id; also node id on NUMA */ unsigned int sp_nrthreads; /* # of threads currently running in pool */ + unsigned int sp_nrthrmin; /* Min number of threads to run per pool */ unsigned int sp_nrthrmax; /* Max requested number of threads in pool */ struct lwq sp_xprts; /* pending transports */ struct list_head sp_all_threads; /* all server threads */ @@ -72,7 +73,7 @@ struct svc_serv { struct svc_stat * sv_stats; /* RPC statistics */ spinlock_t sv_lock; unsigned int sv_nprogs; /* Number of sv_programs */ - unsigned int sv_nrthreads; /* # of server threads */ + unsigned int sv_nrthreads; /* # of running server threads */ unsigned int sv_max_payload; /* datagram payload size */ unsigned int sv_max_mesg; /* max_payload + 1 page for overheads */ unsigned int sv_xdrsize; /* XDR buffer size */ @@ -448,8 +449,9 @@ struct svc_serv * svc_create_pooled(struct svc_program *prog, unsigned int bufsize, int (*threadfn)(void *data)); int svc_set_pool_threads(struct svc_serv *serv, struct svc_pool *pool, - unsigned int nrservs); -int svc_set_num_threads(struct svc_serv *serv, unsigned int nrservs); + unsigned int min_threads, unsigned int max_threads); +int svc_set_num_threads(struct svc_serv *serv, unsigned int min_threads, + unsigned int nrservs); int svc_pool_stats_open(struct svc_info *si, struct file *file); void svc_process(struct svc_rqst *rqstp); void svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp); diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index dd22906705f1a..92bad06755efd 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -820,9 +820,14 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) * svc_set_pool_threads - adjust number of threads per pool * @serv: RPC service to adjust * @pool: Specific pool from which to choose threads - * @nrservs: New number of threads for @serv (0 means kill all threads) + * @min_threads: min number of threads to run in @pool + * @max_threads: max number of threads in @pool (0 means kill all threads) + * + * Create or destroy threads in @pool to bring it into an acceptable range + * between @min_threads and @max_threads. * - * Create or destroy threads in @pool to bring it to @nrservs. + * If @min_threads is 0 or larger than @max_threads, then it is ignored and + * the pool will be set to run a static @max_threads number of threads. * * Caller must ensure mutual exclusion between this and server startup or * shutdown. @@ -832,16 +837,36 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) */ int svc_set_pool_threads(struct svc_serv *serv, struct svc_pool *pool, - unsigned int nrservs) + unsigned int min_threads, unsigned int max_threads) { - int delta = nrservs; + int delta; if (!pool) return -EINVAL; - pool->sp_nrthrmax = nrservs; - delta -= pool->sp_nrthreads; + /* clamp min threads to the max */ + if (min_threads > max_threads) + min_threads = max_threads; + + pool->sp_nrthrmin = min_threads; + pool->sp_nrthrmax = max_threads; + + /* + * When min_threads is set, then only change the number of + * threads to bring it within an acceptable range. + */ + if (min_threads) { + if (pool->sp_nrthreads > max_threads) + delta = max_threads; + else if (pool->sp_nrthreads < min_threads) + delta = min_threads; + else + return 0; + } else { + delta = max_threads; + } + delta -= pool->sp_nrthreads; if (delta > 0) return svc_start_kthreads(serv, pool, delta); if (delta < 0) @@ -853,6 +878,7 @@ EXPORT_SYMBOL_GPL(svc_set_pool_threads); /** * svc_set_num_threads - adjust number of threads in serv * @serv: RPC service to adjust + * @min_threads: min number of threads to run per pool * @nrservs: New number of threads for @serv (0 means kill all threads) * * Create or destroy threads in @serv to bring it to @nrservs. If there @@ -867,20 +893,23 @@ EXPORT_SYMBOL_GPL(svc_set_pool_threads); * adjusted; the caller is responsible for recovery. */ int -svc_set_num_threads(struct svc_serv *serv, unsigned int nrservs) +svc_set_num_threads(struct svc_serv *serv, unsigned int min_threads, + unsigned int nrservs) { unsigned int base = nrservs / serv->sv_nrpools; unsigned int remain = nrservs % serv->sv_nrpools; int i, err = 0; for (i = 0; i < serv->sv_nrpools; ++i) { + struct svc_pool *pool = &serv->sv_pools[i]; int threads = base; if (remain) { ++threads; --remain; } - err = svc_set_pool_threads(serv, &serv->sv_pools[i], threads); + + err = svc_set_pool_threads(serv, pool, min_threads, threads); if (err) break; } -- 2.47.3