From patchwork Mon Jul 10 16:42:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13307393 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1622EB64D9 for ; Mon, 10 Jul 2023 16:42:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230281AbjGJQmk (ORCPT ); Mon, 10 Jul 2023 12:42:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230264AbjGJQmj (ORCPT ); Mon, 10 Jul 2023 12:42:39 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3981180 for ; Mon, 10 Jul 2023 09:42:35 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 502066101E for ; Mon, 10 Jul 2023 16:42:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C2CCC433C7; Mon, 10 Jul 2023 16:42:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689007354; bh=xe3T/z5HwAy1RnUi4f9GXor1QkLrb5tcWJETBoFq88I=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=lcgXl0lHYX2Ue8rvjO8Re1erqlxLNZrsGRkMRyvFRYV4ZpOHjTgBV6AASl6t7+md0 9RLxkA0RFImwDfkbBpfEv8TIncFv/bNU4O85ie+eaNC3kbP9okwVeKRtLnHcn6mfbD gl5aT0fwRLynRtjY5AN+99ReLPHQaKgBWooh4Zq+HOvaaun7hLOAYNFdvz22Qfbzu6 hb38d7PonlINBBtFEWIu/WfFIoJG051KLemvztB2RGVcQ8JiGi+yq17OLICnFv5Oqc DqPZfXqh/RmC+zIaKPBgEq06sW8fJv0AW8qqXc+nzhr9oAK3TNf7mUAvVhXKb7wpTs JAstn15YH22iA== Subject: [PATCH v3 6/9] SUNRPC: Clean up svc_set_num_threads From: Chuck Lever To: linux-nfs@vger.kernel.org Cc: Chuck Lever , lorenzo@kernel.org, neilb@suse.de, jlayton@redhat.com, david@fromorbit.com Date: Mon, 10 Jul 2023 12:42:33 -0400 Message-ID: <168900735334.7514.10614943419985083955.stgit@manet.1015granger.net> In-Reply-To: <168900729243.7514.15141312295052254929.stgit@manet.1015granger.net> References: <168900729243.7514.15141312295052254929.stgit@manet.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Chuck Lever Document the API contract and remove stale or obvious comments. Signed-off-by: Chuck Lever --- net/sunrpc/svc.c | 60 +++++++++++++++++++++++------------------------------- 1 file changed, 25 insertions(+), 35 deletions(-) diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index b7a02309ecb1..b02a672aaada 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -728,23 +728,14 @@ struct svc_rqst *svc_pool_wake_idle_thread(struct svc_serv *serv, return NULL; } -/* - * 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) +static struct svc_pool * +svc_pool_next(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) { - if (pool != NULL) - return pool; - - return &serv->sv_pools[(*state)++ % serv->sv_nrpools]; + return pool ? pool : &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) +static struct task_struct * +svc_pool_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) { unsigned int i; struct task_struct *task = NULL; @@ -752,7 +743,6 @@ choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) 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); @@ -767,21 +757,15 @@ choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) 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); set_bit(RQ_VICTIM, &rqstp->rq_flags); list_del_rcu(&rqstp->rq_all); task = rqstp->rq_task; } spin_unlock_bh(&pool->sp_lock); - return task; } -/* create new threads */ static int svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { @@ -793,13 +777,12 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) do { nrservs--; - chosen_pool = choose_pool(serv, pool, &state); - + chosen_pool = svc_pool_next(serv, pool, &state); node = svc_pool_map_get_node(chosen_pool->sp_id); + rqstp = svc_prepare_thread(serv, chosen_pool, node); if (IS_ERR(rqstp)) return PTR_ERR(rqstp); - task = kthread_create_on_node(serv->sv_threadfn, rqstp, node, "%s", serv->sv_name); if (IS_ERR(task)) { @@ -818,15 +801,6 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) return 0; } -/* - * 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. Caller must ensure that mutual exclusion between this and - * server startup or shutdown. - */ - -/* destroy old threads */ static int svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { @@ -834,9 +808,8 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) struct task_struct *task; unsigned int state = serv->sv_nrthreads-1; - /* destroy old threads */ do { - task = choose_victim(serv, pool, &state); + task = svc_pool_victim(serv, pool, &state); if (task == NULL) break; rqstp = kthread_data(task); @@ -848,6 +821,23 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) return 0; } +/** + * svc_set_num_threads - adjust number of threads per RPC service + * @serv: RPC service to adjust + * @pool: Specific pool from which to choose threads, or NULL + * @nrservs: New number of threads for @serv (0 or less means kill all threads) + * + * Create or destroy threads to make the number of threads for @serv the + * given number. If @pool is non-NULL, change only threads in that pool; + * otherwise, round-robin between all pools for @serv. @serv's + * sv_nrthreads is adjusted for each thread created or destroyed. + * + * Caller must ensure mutual exclusion between this and server startup or + * shutdown. + * + * Returns zero on success or a negative errno if an error occurred while + * starting a thread. + */ int svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) {